And Now, More Mobile Voice With VoWifi!

Potential Trouble Points Including Handovers (Mobile to Wifi), Wifi to VoIP (SIP and RTP) Translation, and Finally, Measurement of Voice Quality
voice over wifi

VoWifi (Voice over Wifi) allows cable companies and Multiple System Operators (MSOs) to offer a competitive mobile voice offering with superior voice quality in housing, office and other inside building areas that suffer from poor mobile cell coverage. Similarly, mobile operators can hand over voice calls from their mobile networks to local Wifi networks, freeing facilities and taking advantage of the coverage afforded by Wifi hot spots. No longer will consumers have to rely on the positioning of cell towers; they can now gain quality communications from the gateway in their home!

With the rollout of iPhone 6, Verizon subscribers got their first taste of VoWifi, which is a VoIP voice and SMS/MMS service exercised over Wifi networks. With VoWifi, mobile subscribers receive a seamless voice and messaging experience as they move between cellular networks and Wifi networks in their home, office or elsewhere.

VoWifi can be both a complement and supplement for cellular voice services. Where cell coverage is lacking, VoWifi can provide high performance mobile service, and in metropolitan areas with dense Wifi coverage, it can actually substitute for a cellular network. VoWifi also provides a low cost international roaming solution for users allowing them to take advantage of home, office or any available Wifi network. Indeed, VoWifi increases the value of home or office Wifi access, expanding it from Internet access to allow voice services to run over the top of it.

As with any IP service offering, VoWifi brings both a new and familiar set of challenges to service assurance. There is a complexity to Wifi network and VoWifi session flows that must be tackled by service assurance tools. These tools provide monitoring coverage for key, underlying procedures that enable consumers to connect to the service, as well as potential trouble points including Handovers (mobile to Wifi), Wifi to VoIP (SIP and RTP) translation, and finally, measurement of Voice Quality.

To gain access to a Wifi network, all users must be authenticated and granted access. There are approximately 30 procedures (messaging with multiple protocols) to connect a smartphone, tablet, PC or other device (such as a wearable) to a Wifi network. Once the user is connected the voice or data session can be established. For a voice call it can be handed over from a mobile network, transferring the SIP signaling and RTP voice media to the Wifi internet connection, or it can be established anew directly from the Wifi access. The Mobile to Wifi handover has critical procedures (messages) that must function properly for this seamless connection to occur. Increased latency, packet drops and errors will lead to dropped calls and consumer frustration. Poor voice quality due to packet impairments, such as jitter, latency, loss, gaps and bursts, will further hurt the experience of the VoWifi service.

Monitoring the Access and Authentication procedures provides assurance that users can connect to Wifi hot spots, and analyzing the success/failure metrics, their availability can be viewed and reported on. Similarly, monitoring the success/failure of handovers provides key visibility to a potential trouble spot.  Having aggregated session KPIs that can be broken down into individual sessions provides rich troubleshooting information to address any service issues. And finally, monitoring voice quality and packet impairment issues provides key indicators to manage the user experience for the actual voice calls.

To complement or supplement VoLTE, VoWifi must offer a reasonable facsimile of service level and voice quality, else it becomes a “best effort” service that is to be avoided for any conversation that really matters. A proactive monitoring and troubleshooting solution is needed to assure the availability of the Wifi hotspots, the ability of users to gain access to the Wifi network, the effectiveness of handovers between mobile and Wifi networks and the voice quality of the Wifi communications.