CableLabs in PacketCable , which adopted also the IMS architecture but has no USIM/ISIM capabilities in their terminals, published deltas to the 3GPP specifications where the Digest-MD5 is a valid authentication option. Later on, TISPAN also did a similar effort given their fixed networks scopes, although the procedures are different. To compensate for the lack of IPsec capabilities, TLS has been added as an option for securing the Gm interface. Later 3GPP Releases have included the Digest-MD5 method, towards a Common-IMS platform, yet in its own and again different approach. Although all 3 variants of Digest-MD5 authentication have the same functionality and are the same from the IMS terminal's perspective, the implementations on the Cx interface between the S-CSCF and the HSS are different.