How network will know that UE is supporting IMS network or not?

Question

if ENB requests ue capability through UE capability enquiry message .In UE capability enquiry message enb includes eutra and utra.Now if UE is not supporting eutra how enb will know about this

Answer 1

During the Attach Request(UE->N/W), UE sends it's capability information.
If a UE support VoLTE, UE would set its capability in Attach Request as
Voice domain preference and UE's usage setting
UE's usage setting: Data centric
Voice domain preference for E-UTRAN: IMS PS voice preferred, CS Voice as secondary
If UE sets these IEs to be 'Voice Centric' and 'CS Voice Only', it is highly likely that UE does not support VoLTE or VoLTE functionality is temporarily unavailable

Comments

Voice domain preference for E-UTRAN: IMS PS voice preferred, CS Voice as secondary---- please yeh thoda explain kare mujhe clear nahi hui yeh line

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Hi,
So let's say if your mobile is supporting VoLTE, in that case your voice preference would be  IMS PS voice, in case of fallback or UE doesn't support VoLTE it will be CS voice.
There are multiple option for Voice domain preference for E-UTRAN:
1. CS voice only
2. IMS PS voice only
3. CS voice preferred, IMS PS voice as secondary
4. IMS PS voice preferred, CS voice secondary

So based of UE capability, UE selects one of these option and send in Attach Request

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Thanx