Call transfers to IP phones from Caller System Transfer do not take place in the Cisco Unity 4.x. The call is transferred to the Cisco Unity main greeting instead of to the IP phones.
There are different possible reasons for this issue. In order to resolve this issue, complete these steps:
Check the voice mail ports that the calling search space (CSS) has access to in the partition of the IP phones.
Check the Restriction tables in Cisco Unity. The Caller System Transfer uses CS_Default_System_Transfer, by default. If CS_Default_System_Transfer restricts all outbound calls with No configured for *, then make a new rule x??? and say Yes.