CODEWITHSUNDEEP
telecommunicationlte4g
Zack kumar
Zack kumar

Reputation: 13

Difference between Cellular calls and VoIP calls in LTE?

What is the difference between Cellular calls and VoIP calls in LTE. As both use IP packets to send data to EPC. Without internet VoIP calls doesn't work but cellular calls work. Am I missing something?

Upvotes: 1

Views: 739

Answers (2)

Breno
Breno

Reputation: 66

VoLTE calls are the true operator calls, made directly on the phone dialer and whose audio packets go through your carrier's 4G IMS network. VoLTE calls are a type of VoIP call (such as VoLTE, VoWifi, VoNR). They use a dedicated EPS bearer that has controlled quality of service determined by your carrier. If your operator or your phone doesn't support VoLTE/IMS, your phone will fallback to 2G/3G to complete the call. This is not a VoIP call, but a CS (circuit-switched) call -- as 2G/3G are not PS (packet-switched) networks.

So the "cellular calls" in LTE are also VoIP calls -- they're just not OTT (over-the-top) VoIP calls.

These OTT VoIP calls (WhatsApp/Skype/Zoom calls) are calls made by applications that can only use the default internet bearer, so they don't have guaranteed quality of service for that data bearer. Packet delay (latency), packet loss, priority and bitrate parameters are completely different for that bearer.

These OTT VoIP calls lack very important features such as CS fallback, call continuity (SRVCC), supplementary services and most importantly emergency services (911).

Upvotes: 0

TCPIP
TCPIP

Reputation: 1

A VoIP call will be treated as internet traffic, that is best effort internet traffic. It will travel over the air, to the EPC and then on to the public internet. The mobile operator will handle it as any other internet traffic. The mobile operator will not do any call handling.

A 'cellular' call will be treated by the mobile operator as true VoIP. It will have associated quality of service (focus on latency). It will be handled by the operator call control platform. If going to another network it will be sent over a private IP network, again guaranteeing quality of service.

Now, in practice, the best effort public internet might just be more than good enough.

Upvotes: 0

Related Questions