Hi Sudheer,
Here is an example of the config changes to be done on CME (Communications Manager Express)
Basic Call Forwarding: Example
The following example sets up forwarding for extension 2777 to extension 2513 on all calls, busy, and no answer. During night service hours, calls are forwarded to a different number, extension 2879.
For Phone A
ephone-dn 20
number 2777
call-forward all 2513
call-forward busy 2513
call-forward noan 2513 timeout 45
call-forward night-service 2879
http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/admin/configuration/guide/cmetrans.html#wp1106692
Then for Phone B
ephone-dn 21
number 2513
call-forward all
call-forward busy XXXX (where XXXX is the Cue Pilot #)
call-forward noan XXXX timeout 45 (where XXXX is the Cue Pilot #)
You can check this for CUE;
**Mailbox selection (OCN or LRD) in your case use OCN
This configurable option specifies the mailbox to be used in case of call forward.
Mailbox selection: Mailbox in which an incoming voice message is stored. The options are original called number (OCN) or the last redirected number (LRD). LRD is the default option:)
Check out Page 88 of this good doc;
http://www.cisco.com/en/US/docs/voice_ip_comm/unity_exp/rel2_3/cliadmin/cuecli23.pdf
Hope this helps!
Rob