What is VoLTE and what do you need to use it?

The VoLTE stands for Voice Over LTE.  LTE is a network that belongs to the fourth generation of telecommunication.  The earlier generations 2G and 3G, use two separate subnetworks for voice and data, while LTE has only a data network.  This brings a new way for voice calls to work. A virtual voice circuit needs to be set up over a packet network.

Before VoLTE, a subscriber could use a data network for web browsing, and other activities over the Internet.   The VoLTE opens new options for subscribers and network operators. The best part is that now operators no need to maintain two separate networks one for data and the other for the call.

To access Voice Over LTE, you need to upgrade the phone and need to check with the mobile operator. These days most mobile operators support it.

What is VoLTE?

As we have talked about, it’s voice over a mobile data network.  What will change if you get such a thing?  It’s the speed it can offer which may bring a richer experience.  In an earlier network, the voice was using the SS7 network. In that, for a call, there was a dedicated E1/T1 circuit for voice packets transfer. Although the bandwidth was reserved, it was with an upper limit (not so high).

With LTE, data speed enhanced as compared to the previous generations, but the call was still on a 3G network.  When there is a voice call, the phone switches to 3G, and after the call again switch back to 4G-LTE.  Makes a temporary disconnect with the data. With VoLTE, there will be no such thing.

With VoLTE a call can use much more bandwidth, which results in High Definition(HD) video and audio calls.

Advantages of VoLTE-

  • The call connects much faster and the call quality is much better because of the faster speed.
  • You can browse data and at the same time can talk to someone over Voice.
  • Brings more services as all have moved to the IP protocols for telephony.

Disadvantages –

Can not work on a basic phone, those do not have data capability at all. A mobile operator always needs to set a parallel network for Voice at least in some area.

What does a subscriber need to use VoLTE?

For a mobile subscriber, the phone should be VoLTE capable.  If not he has to upgrade the phone.  Once you are sure that the serving mobile operator supports the feature, you need to enable it in the handset.

How to enable it on Android? 

What mobile operators need to support the VoLTE?

Looks that it’s very simple to support the new calling feature. But it is not so. First, an operator upgraded to 4G-LTE from the previous 3G. The up-gradation process includes purchasing spectrum, deploying radio, and wired network components.  Newer network components bring new protocols. For example, the diameter is the new protocol in 4G roaming while in 3G SS7 was the protocol.

Now data is on with over 4G, but still, voice uses 3G fallback.  With Voice Over LTE, no more fallback will happen. But require new network components with additional protocols. IMSI is the core network for VoWifi. It uses primarily Session Initiation Protocol and with other protocols e.g GTP.

Within IMS, sim becomes ISIM and it does on IMS network attach for Voice Call, SMS, USSD, etc.

Is WiFi calling is same as VoLTE?

Looks like both are IP-based but on a network level, both are far apart. The WiFi network is a non-3GPP network, that requires an additional ePDG to support Wifi Calling.  While VoLTE uses the same 3GPP network.

In VoLTE, the data is consumed from the subscriber data bundle, while in WiFi Calling data is used from the WiFi account.