How will UE use MCC MNC values (p-access-network-info header) in LTE-IMS integration?

Question

When a UE is doing IMS registration, it will bring p-access-network-info header in the register message. There's MCC MNC value within this header, my question is :

How will UE use MCC MNC values? depends on the MCC MNC broadcast from eNB or using IMSI in the UE?

Is there any document describing this?

Answer 1

Header P-Access-Network-Info captures the access network as perceived by the UE and communicated to IMS.

For LTE it is either access-type= 3GPP-E-UTRAN-FDD or 3GPP-E-UTRAN-TDD and UMTS it is UTRAN-cell-id-3gpp parameter which assumes the value of CGI footprint where UE is located.