This TS specifies procedures and protocol elements for tunnelling of IMS traffic over restrictive access
networks, specifically procedures and protocol elements for establishing, maintaining, and sending traffic via a firewall
traversal tunnel between the UE and an enhanced firewall traversal function (EFTF) in the network. The present
document is applicable to UE and EFTF.
The present document applies only to the case when the IMS traffic is not routed via EPC of a PLMN. Procedures for
tunnelling of IMS traffic that is routed via EPC are specified in TS 24.302 annex F