12.0(7)T and 12.0( 8) are very old images and i would not recommend the use of it. Also 12.1(5)T6 is a deferred image and you should move away from that image.
I checked 12.1(5)T7 for you and it works just fine. Upgrade to 12.1(5)T7 or 12.2 images.
c2600-1(config-voiceport)#cp ?
locale 2 letter ISO-3166 country code
AR Argentina IN India PE Peru
AU Australia ID Indonesia PH Philippines
AT Austria IE Ireland PL Poland
BE Belgium IL Israel PT Portugal
BR Brazil IT Italy RU Russian Federation
CA Canada JP Japan SA Saudi Arabia
c2600-2(config)#dial-peer voice 234 ?
pots Telephony
voatm Voice over ATM
vofr Voice over Frame Relay
voip Voice over IP
c2600-2#sh ve
00:01:39: %SYS-5-CONFIG_I: Configured from console by consoler
Cisco Internetwork Operating System Software
IOS (tm) C2600 Software (C2600-IS-M), Version 12.1(5)T7, RELEASE SOFTWARE (fc1)
TAC Support: http://www.cisco.com/cgi-bin/ibld/view.pl?i=support