[cisco-voip] SIP Trunking with UCM 5.x - 7.x

[Mark Holloway]

In an effort to help customers migrate away from PRI and move towards SIP Trunking with an ITSP I'm trying to notate any major differences in SIP Trunking operation between UCM 5.x, 6.x, and 7.x.  My intentions are to use CUBE between UCM and the ITSP and I would like to support all 3 major versions if possible.  The Cisco ISR running CUBE will act as a b2bua and handle SIP registration and header manipulation (if necessary).  Can anyone comment on any major feature differences among the 3 major versions of UCM as it relates to SIP trunking?  

Regards,
Mark