Trai Releases Consultation Paper on Fixing Quality of Service Norms for VoLTE Networks

Accordingly, from a DCR benchmark and measurement perspective, a network’s performance on all technologies, for example, 2G, 3G or 4G deployed by the TSP in an LSA and used for providing voice services are treated equally. After this amendment, the consolidated data of all the cells of the TSP is being used to assess as part of a single network, irrespective of the technology being used, i.e. whether cells belongs to GSM, CDMA, WCDMA or LTE.

As you all might be aware of, LTE is an all-lP, data-only transport technology based on packet switching. Voices services in LTE network is mainly carried by two technologies viz. Voice over LTE (VoLTE) and Circuit Switch Fall Back (CSFB). VoLTE allows carriers to transmit voice calls over LTE network and controlled through their IP Multimedia Subsystem (IMS). This means that voice calls and data sessions travel side-by-side over LTE. Whereas in CSFB, LTE network is used only for data traffic and voice services are provided on traditional circuit-switched technologies of 2G and 3G. CSFB redirects a device registered on the LTE network to the 2G/3G network (i.e. fallback) prior to originating or receiving a voice call.

To provide voice services via LTE, both VoLTE and CSFB techniques may face some quality of service issues due to different network scenarios. Such scenarios may result in silence period or voice mute observed by the users. The extent to which this is experienced by the user during a call before dropping of the call may also be implementation specific said Trai in the paper.