Can a VoLTE Call Data flow on IMS Default Bearers?

Question

In Other Words VoLTE Call Established and No Dedicated Bearers established by NW, Is it Possible the call will be stable ? Can It use IMS Defaulr Bearers for the Call?

Answer 1

Hi yadav,

As per my understandings QOS 1 is for conversational voice and QOS 5 is for IMS signalling. so with IMS PDN you can create QOS 5 as default bearer and use it for IMS signalling then you can create dedicated bearer with QOS 1 for IMS data flow. But if you use same IMS signalling you will not face any problem instead you will get good clarity because QOS 1 and QOS 5 is of same property with only priority change (QOS 5 is having higher priority than QOS 1).

Note : you will face problem if you use default bearer for IMS calling when you have more GBR(guaranteed bit rate ) dedicated users. because default bearer is always an N-GBR so there is no guarantee for constant bit rate.

Comments

Thanks Jaganathan for the reply. So You mean to say that there should not be any problem for the Voice if Dedicated Bearers not established. But I have observed that for some operators if Dedicated Bearers didnt established then Call will be dropped after Tqos timer expiry. But Few Operators the Call is still stable and it uses Default bearers for RTP. Is is still Valid?

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Yes it is. It is depends on the operator implementation. If operator supports an default bearer RTP transfer then you can make it.

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So Finally these things are Operator Specific. Thanks for your reply.

Answer 2

Yes it is possible , but it depend also on handset chopset