Voice Over Wi-Fi (VoWi-Fi or Wi-Fi Calling)

Transcription

1 Voice Over Wi-Fi (VoWi-Fi or Wi-Fi Calling)

2 Wi-Fi Calling in Ascendance Making voice calls over Wi-Fi isn t a new idea but new network capabilities and architectures are opening opportunities for cellular carriers to develop business models built around Voice over Wi-Fi. In the beginning and for a very long time there was only the Public Switched Telephone Network (PSTN) that was until recently the only way to connect telephones, both fixed and eventually mobile. The PSTN network girds the earth, enabling communication as long as the caller knows the phone number that is, the international public telecommunication numbering plan s E.164 number. The PSTN is a hierarchical hop-by-hop network controlled by telephone companies (telcos) that charge for the privilege of using it. The further away the two telephones are, the more the call costs. Then in the 1990s, along came the Internet and changed the equation: no longer did the cost of a connection depend on the distance between two points. Soon, people were trying to drive telephony through the Internet. The idea was that while the call setup would still be hop-by-hop, the media voice and video would flow peer-to-peer between the two endpoints. Today, most telephones are in fact mobile phones, and in more and more markets, most mobile phones are smartphones. When a smartphone user is at home or at work or at a Wi-Fi-enabled public location their smartphone connects to the Internet over Wi-Fi. When a smartphone is connected via Internet telephony, it is using Voice over Wi-Fi (VoWi-Fi). By and by, the Session Initiation Protocol/Real-time Transport Protocol (SIP/RTP) model became the de-facto Internet telephony interworking standard. With it, a new kind of address emerged the network access identifier (NAI), defined in its present form by RFC 7542 which most people know as the address format. Unlike E.164, NAI contains digits, uppercase and lowercase letters from the English alphabet, a selection of punctuation marks, and Unicode characters, specifically, UTF8 (Unicode Transformation Format 8-bit) encoded in 2, 3 or 4 bytes. But there was a problem. The Internet uses 4-byte addresses that can identify at most 4 billion endpoints. Today, there are 7 billion human beings on the planet with projections from the United Nations of 9.6 billion by A transition to a 16-byte address is required to accommodate the population growth, but a sudden big bang global cutover would be incredibly expensive. The default response, then, is to put it off until tomorrow. In the meanwhile, the Network Address Translation (NAT) is keeping the Internet economy alive. While NAT works fine for the World Wide Web, it plays havoc with the peer-to-peer nature of Internet SIP/RTP telephony and essentially makes it unusable in the hands of the non-technical user. Enter the over the top (OTT) apps providers. This class of services includes not only Apple s Facetime, Facebook s WhatsApp, Google s Hangouts & Allo and Microsoft s Skype, but also Viber, Line, WeChat and many more. Earlier, such apps would have their own addressing scheme for example, the erstwhile Skype Name but these days they all seem to have settled on using, after verification, either addresses or telephone numbers. These services make Internet telephony completely idiot-proof for the end user and come with a very attractive pricing plan of $,,, or 0.00 per call as long as the call is to someone else within the app s own walled garden. 2

3 Moreover, when Wi-Fi connected smartphones use these apps, their users are experiencing VoWi-Fi. (See Figure 1.) Internet PSTN DID Dialer RFC 7542 NAI e.g. E.164 Number e.g Traditional Telephony (Analog, ISDN, Managed SIP, ) Figure 1: The PSTN-Internet relationship PSTN, Internet and the walled gardens in relation to one another Because the market is intensely competitive, these walled gardens won t talk to one another. This is deliberate, and a part of their business models. If a user is on one of these apps and another user is on another, and both the apps use their respective telephone numbers for addressing, they still cannot call each other. Some of these apps support calling to-and-from the PSTN on a chargeable basis, where incoming calls require the user to rent a telephone number from the app provider, while outgoing calls are charged by the minute. Google Voice Dialer Skype Number Skype Out Internet Telephony (SIP, ) Walled Gardens Even now, the PSTN with its E.164 telephone numbers is the baseline network for telephony. Which begs the question: What if smartphones could have a Wi-Fi calling system that was native to the PSTN? A new model for Voice over Wi-Fi Consider the following user experience for outgoing calls if Wi-Fi calls were native to PSTN: Consider the following experience for incoming calls: The other party (who doesn t know whether I m on cellular or Wi-Fi) dials my regular cellphone number. Call from Whether I m on cellular or Wi-Fi, I dial the same number the same way on the same dialer screen. The other party sees the same number (my cellphone number) as caller identity. The other party sees the same number (my cellphone number) as caller identity. Call from So far, this exchange is not very exciting or even novel. After all, some of the OTT apps can provide more or less the same experience. However, things get interesting when the user starts walking around when a call is in progress and the smartphone has to bounce back and forth between Wi-Fi and cellular. 3

4 Cellular networks are usually very good at covering outdoor spaces within their footprint and can also attempt targeted coverage of selected indoor locations. However, in general, walls and floors are bad for radio propagation, so indoor coverage can be challenging where the carrier has not made an effort. This can include homes where people with cellphones spend a significant amount of time. On the other hand, a large and growing number of indoor locations have Wi-Fi networks: homes, workplaces, colleges and universities, airports, shopping malls and cafés. The problem is cellphone access ends when the user leaves the location.in a sense, cellular and Wi-Fi signals are complementary. Consider the following handover scenarios between the two: For the typical cellphone user, the policy could be as simple as the following: For the power user, it could be as elaborate as this: Wi-Fi Calling Wi-Fi For the power user, it could be as elaborate as this: Wi-Fi Calling Wi-Fi Calls Only Wi-Fi Calls Preferred Cellular Calls Preferred Cellular Calls Only Cellular Handover Automatic Prompt Disable Wi-Fi Calling Prompt if Roaming Disable if Roaming A call is in progress through cellular, when the my phone decides to switch it to Wi-Fi OR A call is in progress through Wi-Fi, when the my phone decides to switch it to cellular Wi-Fi if and only if Roaming Prefer Wi-Fi if Roaming Wi-Fi Calling Ignore Untagged Networks The handover is seamless: neither I nor the other party in the call has to take any action, and there is zero-to-minimal disruption perceived in the voice (and if applicable, video) path. The decision is based on my policy configured on my phone a-priori, a policy that takes into account the signal (availability and quality) of the cellular network and Wi-Fi networks. Prefer Tagged Wi-Fi Networks Tag Wi-Fi Networks Wi-Fi Cellular Handover Auto-tag Operator Networks Alpha Bravo Today, however, no OTT app is capable of doing this. To flip a call back and forth between cellular and Wi-Fi connections requires explicit support from the cellular operator, something an OTT application cannot expect to get. However, the policy in a user s phone is their own, and what they can define is limited only by the options that the manufacturer of the phone chooses to expose to them. The carrier whether it provides the home network or a public network has no say in the matter. The power-user s configuration can make the handover non-seamless if that is what they really want by choosing the Prompt handover option. Alternatively, they can set and change their defaults. For example, by choosing Wi-Fi Calls Preferred, their default is to use Wi-Fi networks for Wi-Fi calling. The richness of the policy selection is up to the creativity of the manufacturer of the phone. 4

5 1 Making the Case for QoS Cellular carriers have an uneasy relationship with OTT VoWI-FI apps, as they clearly see them as a threat to their telephony revenue. The stick that Carriers could use to beat the OTT apps is quality of service (QoS). The argument is that since the Internet is a best effort network, the quality bit-rate, delay, packet drops of any traffic path through the Internet cannot be guaranteed. However, quality is something that Carriers can effectively guarantee, from a QoS standpoint, with their licensed spectrum and managed backbone networks. Indeed, cellular carriers can trace a QoS-safe path from the terminal to a telephony service exclusively through the cellular radio-access network (RAN) and the operator s core network. In comparison, an Internet-based OTT app will have, by definition, an unsafe QoS path. (See Figure 2, the cellular RAN path is highlighted in green and the OTT app s path in yellow.) Unfortunately, for cellular carriers, they cannot guarantee a safe QoS user experience for any native Wi-Fi calling services they promote. The only way for the Carrier to avoid any taint of yellow in their service is to extend its managed backbone to the Wi-Fi, which, in practice, is possible only for selected public indoor spaces. It is clearly infeasible to hook up all homes that way, and a native Wi-Fi calling service can only expect mass adoption if it works through any Wi-Fi that connects to the Internet, including those in homes. Perhaps a reexamination of the quality of service (QoS) question is in order for cellular carriers. 01 The user s expectation is that the Carrier s quality of service assurance is a guarantee that the stated quality will be provided. However, it only really means that the Carrier will set up the call only if it can guarantee the quality. Therefore, if the Carrier cannot assure the quality of the call, it will not set it up. 02 In the cellular environment, with its variable radio propagation and mobility, this further means the Carrier will continue a user s call for as long as it can guarantee the quality of service. If there is sufficient degradation in the quality that can be physically assured, the call may be dropped. 03 This means that quality of service is really about priority while sharing resources and priority is significant only where there is scarcity. Over the years, broadband services have improved so much in most economies that data bandwidth over most consumer-grade wireline Internet connections is no longer a scarce resource. While still technically a best effort network (and thus unable to actually assure anything), cellular carriers can easily provide sufficiently good traffic paths for telephony traffic for most of the time. These arguments can justify native Wi-Fi Calling from a QoS standpoint. However, of course, the same arguments rehabilitate the OTT telephony apps as well. However, the OTT Wi-Fi calling services still cannot provide seamless handovers with cellular telephony, so the native version will continue to have an edge, giving cellular carriers a competitive advantage. Wire Wireless Over-the-top Services Public Wi-Fi Wi-Fi Terminal Internet Figure 2: QoS comparison: Wi-Fi vs Cellular QoS comparison between Wi-Fi voice calls and Cellular RAN voice calls VPN Home/Workplace Services Home/ Workplace Wi-Fi & Network Wi-Fi Terminal Operator Services Operator s Core Network Cellular RAN Cellular Terminal Best-effort (Not QoS Safe) QoS Safe Private 65 Interference-prone

6 2 How Native Wi-Fi Calling is Done The schematic on the left details the Unlicensed Mobile Access (UMA) Wi-Fi calling architecture introduced in 2005 before the smartphone market exploded. The schematic on the right is IMS over Wi-Fi, the dominant architecture in use today. The idea of native Wi-Fi calling is not new in fact, it predates LTE. The idea of Unlicensed Mobile Access (UMA) was first proposed by Kineto Wireless in 2005, and was eventually accepted into the 3GPP specification family as Generic Access Network (GAN). It even saw a few deployments notably by T-Mobile USA. (See Figure 3.) The idea here was to emulate the RR layer of GSM (the dominant radio technology of the day) over Wi-Fi, while hiding it from network components behind the BSC (or RNC). Specifically, the MSC stayed entirely unaware of the existence of UMA/GAN. Telephony in GSM (and UMTS after it) is circuit-switched (CS), and in UMA/GAN the CS voice bearers were emulated over Wi-Fi using RTP over UDP. Human Human ISDN Call Control Mobility Management ISDN Call Control IMS Call Control Mobility Management GSM-RR/UMTS-RRC RR/RRC emulated over IP GSM-RR/UMTS-RRC GSM/UMTS Air Interface IP over Wi-Fi GSM/UMTS Air Interface IP over LTE IP over Wi-Fi GSM-RR/UMTS-RRC RR/RRC emulated over IP GSM-RR/UMTS-RRC Mobility Management ISDN Call Control In MSC In MSC Mobility Management ISDN Call Control IMS Call Control Network Network Figure 3: Comparison of UMA and IMS over Wi-Fi The concept worked reasonably well, but while handovers between GSM and Wi-Fi were supported in theory, they did not work so well in practice, primarily because the coordination between the two legs at the RR level is very fragile. This particular brand of Wi-Fi calling did not see much growth: in addition to the problem with handovers, there were not too many phones with Wi-Fi as this was before the smartphone market took off. Wi-Fi calling has since been reinvented, and the new way of thinking is illustrated in the schematic on the right side of Figure 3. Interestingly, not a lot of original invention was required, instead users relied on pieces of existing technology that were developed for other purposes. These include: 01 The Evolved Packed Data Gateway (EPDG), which is a component of the Enhanced Packet Core (EPC) network, and allows the carrier to offer packet-data (IP) access services to its subscribers that already have Internet access, including over Wi-Fi. Since the most common use of packet access in cellular networks is to offer Internet connectivity in the first place, the value proposition of this concept is not very obvious. 66

7 ' The IP Multimedia Service (IMS) is the telco version of Voice over IP a beefed-up version of SIP/RTP that is meant to run on a managed IP network in order to assure QoS. Since LTE does not support CS bearers, it offers telephony services using Voice over LTE (VoLTE), which is essentially IMS. The Voice Call Continuity (VCC) concept is needed to ensure continuity of a mobile voice call that can move between packet-switched LTE and circuit-switched GSM/UMTS networks. The key idea here is that for any mobile device that may need this feature, all calls must be anchored in the IMS irrespective of whether it started in GSM/UMTS or LTE. In addition, the IMS must support the signaling necessary to move the mobile-to-anchor voice path back and forth between CS and PS bearers. In the new incarnation, Wi-Fi calling takes a very relaxed and resilient approach towards handovers. For starters, the operation is no longer hidden from the MSC: both the MSC and IMS subsystems are taken into confidence and expected to provide active support. Also, the telephony application the dialer provides active support on the smartphone. (See Figure 4.) CS Access Dialer Client IMS Access IP Address A (for IMS) IMS APN Internet Applications GSM/UMTS CS Bearer LTE PS Bearer Trusted Wi-Fi: SCM/MCM Tunnel PGW IPSEC Tunnel EPDG IP Address B (DHCP) Any Internet Service Provider IP Address C Internet APN Trusted Wi-Fi: SCM/MCM Tunnel PGW MSC IMS Internet Services Figure 4: Voice calls over IMS networks Various paths taken by voice calls over IMS networks 7

8 Between the phone s dialer and the network s IMS subsystem, a voice call can take four possible paths as detailed in Figure 4: 01 In blue, the circuit-switched path is taken when the phone is being served by GSM/UMTS. 02 In red, the VoLTE path is taken when the phone is being served by LTE. 03 In green, the trusted Wi-Fi path is taken. This is a relatively new concept where the phone is connected over a Wi-Fi network that is tightly integrated with the carrier s packet core. Realistically, this is possible only for Wi-Fi networks in select public indoor spaces the same ones to which it makes sense to extend the carrier s managed backbone, as mentioned above. 04 In yellow, the untrusted Wi-Fi path is taken when the phone is connected to the Internet over any Wi-Fi network including those in a home, the office or a public space. Over this network, the phone first establishes a VPN (IPSEC: IKEv2/ESP) tunnel towards the carrier s EPDG, through which it reaches the packet core. The EPDG is the only component of the carrier s core network that must be reachable on the public Internet, where it looks like an ordinary IPSEC VPN server that authenticates incoming connections over EAP using the client s SIM credentials. There is even a standard way of locating a Carrier s EPDG on the Internet as shown in Figure 5. Carrier Country MCC MNC EPDG EE UK epdg.epc.mnc030.mcc234.pub.3gppnetwork.org Vodafone UK epdg.epc.mnc015.mcc234.pub.3gppnetwork.org T-Mobile USA epdg.epc.mnc240.mcc310.pub.3gppnetwork.org Rogers Canada epdg.epc.mnc370.mcc302.pub.3gppnetwork.org Salt Switzerland epdg.epc.mnc003.mcc228.pub.3gppnetwork.org Vodafone Germany epdg.epc.mnc002.mcc262.pub.3gppnetwork.org Orange France epdg.epc.mnc001.mcc208.pub.3gppnetwork.org T-Mobile Netherlands epdg.epc.mnc016.mcc204.pub.3gppnetwork.org A1 Telekom Austria epdg.epc.mnc001.mcc232.pub.3gppnetwork.org Orange Spain epdg.epc.mnc003.mcc214.pub.3gppnetwork.org Reliance Jio India epdg.epc.mnc872.mcc405.pub.3gppnetwork.org Figure 5: Carriers EPDG over internet Illustration of different carriers EPDG over the internet 78

9 In countries such as the US, Canada, Japan and South Korea, where phones co-branded by the Carrier are the norm, the Carrier may choose to hard-code a non-standard EPDG address into the phone instead. For example, AT&T or Verizon may use the following hard code: Carrier AT&T Verizone Country USA USA EPDG epdg.epc.att.net 1, 2 wo.vzwwo.com 3 In Figure 4, the acronym APN stands for Access Point Name and should not be confused with Wi-Fi access points. An APN is the name given by the Carrier to a packet network to which the phone can connect and the 3GPP protocol stack allows a phone to simultaneously connect up to 11 packet networks. When a phone is connected to the Carrier s core network through paths 2 (red: LTE), 3 (green: trusted Wi-Fi) and 4 (yellow: untrusted Wi-Fi), it is actually connected to one or more APNs. Each APN is a completely separate network, independent of any other, and when a phone connects to an APN it is assigned an independent IP address to identify it uniquely on that network. One APN labeled Internet APN in Figure 4 connects the phone to the Internet. Its name is determined by the Carrier, and may or may not be something suggestive such as Internet, WWW, and Web or Net. The APN of most interest in Figure 4 is the one that connects the phone to the IMS network. It is a managed IP network that is not the Internet. This APN should be named IMS if we go by GSMA guidelines. At any instant, the phone interested in telephony must be either registered on a CS network (blue path), or connected to and have an IP address assigned by the IMS APN (red, green or yellow path.) Between the LTE (red), trusted Wi-Fi (green), or untrusted Wi-Fi (yellow) paths, if and when a phone switches from one of these paths to another, the core network ensures that the IP address assigned to the phone on each connected APN does not change. This is IP address A in Figure For untrusted Wi-Fi, it is the one acquired (using IKEv2) over the IPSEC tunnel, and is unrelated to the IP address B that is assigned (using DHCP) by the Wi-Fi network that is being tunneled through. For trusted Wi-Fi, it is the one assigned (using DHCP) by the Wi-Fi network An incoming or outgoing phone call may be set up over any of the four paths: CS, LTE, trusted Wi-Fi or untrusted Wi-Fi. However, how does the handover between these paths work? It turns out that both trusted and untrusted Wi-Fi handovers behave the same way: Both LTE Wi-Fi and Wi-Fi Wi-Fi mobility can take advantage of the fact that the IP address of the phone on the IMS APN does not change across the handover. Consequently, the packet communication on the IMS APN is unaffected, and the call continues without the IMS layer even having to know anything about it. In the other cases, the handover takes advantage of the fact the call path is anchored at a common point in the IMS. After the packet path is switched, the dialer picks up the call from this anchor point. (See Figure 6.) This is conceptually similar to a feature on some PBX systems that allows for parking a call on one extension and picking it up from another extension except that in this case it is not necessary to explicitly park the call. 79

10 Bad connection Call is anchored here Figure 6: Call handover between Cellular and Wi-Fi Call handover between CS, LTE, trusted Wi-Fi and untrusted Wi-Fi networks The signaling for this pickup operation has to take place strictly over the new path, as the old path has to be considered unusable by the time the pickup becomes necessary. For CS Wi-Fi handovers, the dialer places a SIP/IMS call to a special URI (typically, a NAI prefixed by sip:) called the Session Transfer Identifier (STI). For Wi-Fi CS handovers, only numeric addresses can be used in CS call-control signaling. In this case, the dialer places a CS call to a special E.164 format Session Transfer Number (STN) to pick the call up. The calls placed by the dialer in (a) and (b) above are hidden from the user. They are automatic, and do not appear in the dialer s call logs. Since no time-critical RR/RRC, signaling is involved, the anchor can hold on to a call with a bad connection for a reasonable period perhaps a few seconds before deciding to drop it. This gives the dialer the opportunity to pick it up using another kind of access and continue the call. Wi-Fi calling will work even while roaming. (See Figure 7.) In fact, the possibility of cheaper calls while travelling internationally has been one of the selling points of this feature. The figure below illustrates how handovers, the key differentiator of native Wi-Fi calling, can continue to work while roaming. MSC & IMS in Visited Network No Roaming Yes 1. Backhaul outgoing CS calls to MSC in home network (using CAMEL) 2. Disable optimal routing for incoming calls (always use GMSC) Handover works MSC & IMS in Home Network A On Wi-Fi, connect through EPDG of home network Operator Policy C No B While on Wi-Fi, try to connect through EPDG of visited network (last network seen on cellular) Success? Yes MSC & IMS in Visited Network Handover works IMS in Home Network, MSC in Home Network for incoming calls only Disable optimal routing for incoming calls (always use GMSC) Handover works No Handovers Handover for incoming calls only Figure 7: Wi-Fi calling during roaming Wi-Fi calling and handover during international roaming 10 7

11 3 Opportunities Ahead In this scheme of things today, CS Wi-Fi handovers seem somehow unfashionable. However, there are some business models where it could be valuable. Wi-Fi calling is inexpensive to deploy in the network. That s because the feature is supposed to work over any Wi-Fi so the carrier does not have to deploy any Wi-Fi infrastructure. In addition, if the carrier has already rolled out VoLTE, it has almost all the required infrastructure in place except the EPDG. Whatever may be the reason, the VoLTE feature has been slow to trickle down to LTE smartphones in the market. Many models support VoLTE only in their Carrier-specific (and locked) variants. Many that do support VoLTE also support Wi-Fi calling, but with handover limited to LTE Wi-Fi. Today, all four major US carriers AT&T, Sprint, T-Mobile and Verizon support native Wi-Fi calling, as does Rogers in Canada, Salt in Switzerland, and Vodafone and EE in the UK. Both O2 and Three offer app-based Wi-Fi calling services that appear to use the EPDG. All of these Carriers are focused on LTE as a technology, and understandably do not feel the need to invest in services for CS-only (GSM & UMTS) subscribers, including Wi-Fi calling. 01 In the Wi-Fi first model, for example, a mobile virtual network operator (MVNO) might be focused entirely on voice and text messaging revenue, particularly in economies where public Wi-Fi is widely available and where perhaps the MVNO is making it available, such as Comcast in US. Wi-Fi calling will handle voice and text messaging while indoors, through both home and public Wi-Fi. When the user is outdoors, GSM/UMTS CS service from a regular mobile network operator (MNO) can be provided to the user through a bulk purchase of airtime from that MNO. 02 Alternatively, there is an opportunity for an MNO that is entirely focused on voice and texting to appeal to a cost-conscious customer base. It can offer outdoor coverage with its own GSM network using very little spectrum perhaps as little as 1 MHz For the rest of the coverage, it can leverage Wi-Fi calling. The MNO would most likely need to invest in public Wi-Fi coverage in dense public spaces, both indoors or outdoors, to make the model work. To make Wi-Fi calling happen, MVNOs and MNOs need their own home subscriber service, Packet Data Network Gateway, EPDG and IMS functions. All of this can be packed into a Wi-Fi-Calling-in-a-box infrastructure product. 7

12 4 Key Takeaways Wi-Fi calling is an idea whose time has come, and will grow alongside VoLTE, perhaps significantly faster. In addition, there are also some not so obvious opportunities in this technology that are also worth exploring. The global demand for voice telephony is approaching saturation, and there is a critical need for cost reduction. Wi-Fi Calling is a technology that addresses both of these challenges. Aricent Offerings Aricent is a global design and engineering company innovating for the digital era. With 25 years of experience in building communication network equipment over multiple technological generations, we are now ready for the next generation technology solutions like Wi-Fi-Calling. The next-generation Wi-Fi calling works seamlessly for the user regardless of the fact they are connected to LTE or Wi-Fi. Voice calls and messages work just as well from anywhere to anyone. Aricent offers Multimedia Subsystem (IMS) core software framework called IMSLite. IMSLite is a complete IP core network solution that enables IP calls, multimedia services and can be leveraged to support VoLTE & VoWI-FI services. IMSLite is a collapsed IMS core hosting proxy, interrogating and serving Call Session Control Functions (P, I and S-CSCF) that makes it a complete high performance solution. It can run on any commercial-off-the-shelf hardware in a native Linux or any virtualized environment. Aricent s next-generation WI-FI offerings also include an Evolved Packet Data Gateway (epdg) which is critical to the network to enable WI-FI offload to the cellular network for WI-FI Calling. The epdg s/w solution is a collective solution supporting both trusted & un-trusted WI-FI calling. Aricent complements the WI-FI calling offerings with its field proven LTE-EPC solution. The PDN Gateway components provide support for S2a and S2b for connectivity with both trusted and un-trusted WI-FI. The LTE EPC HSS component extends support to the SWm/STa interface for device authentication. 12 7

13 References 1. =0&tstart= T-WI-FI-Calling-Problems/td-p/ /page/ Web_Help/Content/ArubaFrameStyles/Voice_Video/Lync_AL G.htm - 13

14 Contact Avijit Ghosh, AVP and Global R&D Lead About Aricent Aricent is a global design and engineering company innovating for the digital era. With more than 12,000 design and engineering talent and over 25 years of experience, we help the world s leading companies solve their most important business and technology innovation challenges - from Customer to Chip Aricent. All rights reserved. All Aricent brand and product names are service marks, trademarks, or registered marks of Aricent in the United States and other countries. 14