No you should have IMS default bearer IP to make an IMS call, but you don't need any other default bearer IP address (any other PDN connection).
Is it mandatory to establish a separate default bearer to exchange IMS signaling messages between UE and IMS network nodes ? Can't internet default bearer be used for the same ?
Which of the network node initiates dedicated bearer creation for the VoLTE call ?
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?
I was going through IMS call flow and came to know that an IP sec tunnel is established between UE and P-CSCF . I could not find out reasoning behind it.
Is it possible HSS belongs to home network and S-CSCF belongs to visited network for the Cx interface ? If not then why ?