Doesn’t VoLTE interoperability work already?
The answer is ‘yes’, but in order to ensure optimal user experience as VoLTE takes off, we all need to help push the case for VoLTE interoperability forward.
The GSMA is doing its bit to help by pulling together an IR.92 extension to help operators put the necessary network and device parameters in place. The result will be faster interoperability testing and lower costs.
Interoperability is vital if people are to be able to enjoy HD voice quality when using VoLTE, especially when there is inconsistent LTE coverage by national operators. And imagine the marketing kudos that an operator can gain by enabling its subscribers to make fast-connecting HD voice calls to friends on another operator’s network.
At Mobile World Congress 2016, Nokia and Huawei demonstrated live network interoperability with several terminal vendors, including LG, Microsoft and Qualcom. The demo ran on Nokia and Huawei VoLTE networks outside Barcelona, using the network-to-network interface (NNI) between core networks. Although this was quite straightforward, a bigger challenge arose with the terminals. Even when a terminal worked well in both networks, this did not guarantee a successful call between networks. In some ways, such issues are not surprising given the complexities of the market in which there are many more terminal vendors than core vendors, all of whom need to interpret the standards.
MWC also saw much interest in VoLTE roaming, which is not yet implemented globally. The GSMA provides common guidance and is addressing the issue of how operators should use the Local Breakout (LBO) or S8 Home Routing (S8 HR) model for VoLTE roaming.
Discussion of this on our stand at MWC16 turned out to be inconclusive, but it currently looks like S8 HR has the edge, especially for national roaming. What about LBO – will it happen? Well, according to some operators it will take several years, which may be a long time to get global communication using VoLTE. We continue to see roaming technologies coming in phases – today we use CSFB for roaming and tomorrow we may see S8 HR being used. Rich Communications Service (RCS) may also play an interesting role here.
I was pleased to see an impressive operator-hosted RCS demo at MWC 16 as it’s been talked about for years, but hasn’t yet won full industry support. But I often wonder why, because, as the RCS case showed, you don’t even need to consider the apps you communicate with, you simply use RCS for chat, file sharing and so on. Currently these functions are blocked because of various apps on individual devices.