In response to the increasing dependence on mobile data, the attention of the wireless industry has been focused on data at the expense of voice. However, service providers soon realized that their voice and SMS services were still a significant part of their revenue. In addition, subscribers often rate different service providers based primarily on the quality and reliability of voice/SMS services.
Therefore, LTE operators are obligated to provide subscribers with high-quality and reliable voice services. To do so, they can choose from several solutions. This includes not just VoLTE and VoWiFi, but also CSFB (Voice over 2G/3G CS networks).
There are clear motivations to adopt, deploy and maintain each of these voice technologies. The biggest challenge, however, is enabling several of them to coexist in the network. Thus, the challenges of each individual voice technology are compounded, resulting in an even bigger challenge: Voice over X.
Delivering high-quality voice services and voice call continuity over IP networks involves several significant challenges that must be anticipated and proactively addressed, including:
Voice data being real-time in nature is extremely sensitive to impairments. Any packet losses, delays or jitter induced by the network are likely to reflect in the voice quality experienced by the user.
Network resources must not be consumed by data-hungry lower priority applications at the expense of higher priority voice services.
Voice call subscribers can move around, resulting in a variety of mobility scenarios. All these mobility scenarios cause the network to execute handovers, which are among the most complex procedures executed within wireless networks. Not only should the network handover the voice calls without call drops, but also deal with any ongoing data sessions.
Voice services should not only be reliable under normal operating conditions, but they should also be able to handle any network element failures with minimal impact. Network elements are often deployed in pools to provide redundancy to deal with such failures. The transition from failed (primary) elements to backup (secondary) elements has to be executed seamlessly and in near real-time to have minimal impact on ongoing calls or calls setup following the failure.
To learn more about these challenges, read the white paper Voice Is Back, and this Time It Is Crossing all Boundaries. Challenges of Voice over X.