Now days Nortel will want to upgrade your 61c to cpp4 cores with 4.5 and maybe even 5.0. I have heard that it is close out of beta.
With this you will probably get a signaling server with network routing service.
The latest model of phones out ore the 1100 series phones 1120 1140 1150.
To program these in this new scenario you would need to build a virtual loop. Building sets directly registering to an itg card is over due.
Example to build a virtual loop.
LD 97
chg supl
v96 (basically the same method as phantom tn.s but called virtual)
This gives you I believe 61-65 and 81-85 virtual loops, It will tell you in the ntp. (ex. 61-0-0-0 thru 61-0-0-31)
To build for example a 1140 series set.
ld 20
new
i2004
cust 0
tn 61-0-0-0
and so on.
key will be 0 thru 5 and you will have to look in the ntp for other designated keys.
One new thing that you will see in the set programming is the virtual zone that it is in.
This has to do with the zones that you have built in your signaling server.
Keep in mind also that if you do voip enable this 61c you will also have to media cards which are 32 port itg cards, on these cards you build vgw channels. These are nothing more than codecs that translate ip or packet switching to tdm switching.
This is just the tip of the ice berg of what you will be able to do.
Hope this helps.