I have existed voice infrastructure (Nortal based), and we just bought Cisco solution (unified communication manager version 7), is there any way that we can integrate the nortal phones with call manager phones and integrate them as one network.
Any hint or clue will be highly appreciated
It is going to depend on what kind of Nortel solution you have. If you have a new IP based or hybrid you can use sip trunks (or even sip proxy). For the old method with simple TDM based Nortel Option 11/81 PBX would be to use a PRI between the two (with QSIG as your signaling protocol).
Essentially insert a Cisco gateway with T1 PRI ports in the middle. Connect your Nortel to the Gateway on one side, and your Callmanager to the Gateway on the other side.
Below is link to doc for method.
(note, CS1000 is in this doc, but older Option 11/81 integrate same way.
(sip trunk between CS1000 and callmanager).