Other options, such as VoLGA, faded after securing limited operator uptake, and the need to fend off over-the-top messaging/voice services is accelerating many carriers‘ moves to VoLTE and even full IMS (IP Multimedia Subsystem). However, only Verizon Wireless is seriously talking about a swift leap to all-4G coverage and services. Most carriers will go through a multi-year period when their VoLTE and IMS platforms still have to coexist with 2G and 3G in areas where 4G coverage runs out.
The consensus that the most pragmatic solution to this was CSFB, despite its technical limitations, is not as strong as it once appeared. Instead, a group led by Asian operators and vendors – particularly ZTE - is throwing another choice (and acronym) into the ring, pushing the eSRVCC (enhanced single radio voice call continuity) standard. This is an extension of the existing SRVCC solution, which has its own performance challenges.
ZTE, which originally proposed eSRVCC as part of the 3GPP standards, last week claimed the industry‘s first commercial deployment of this technology, in Hong Kong, where ZTE show-cases so many of its LTE developments.
It argues that, as an alternative to CSFB, its system can enable higher quality voice calls and end-to-end quality of service assurance. That, it argues, gives operators a more robust voice platform while they upgrade to VoLTE everywhere, and the two standards are designed to run in parallel.
Tu Jiashun, ZTE‘s VP of core networks, said in a statement: “eSRVCC VoLTE improves call connection time when compared to CSFB solution and shortens handover time when compared to SRVCC solutions. It gives LTE users more options and better service experience.”
eSRVCC was proposed by ZTE at the 3GPP in 2009 and was accepted into Release 10 as a standard technology promotion, and completed in March 2011. Other vendors, such as Alcatel-Lucent, can also support this option, and ZTE claims there is growing operator backing too.