Consider the following scenario:
- In a mixed Microsoft Exchange Server 2007 Unified Messaging (UM) server and Microsoft Office Communications Server(OCS) 2007 environment, the Auto Attendant is configured for unauthenticated callers to call in.
- Dual tone multi-frequency (DTMF) Auto Attendant is only configured to use Key Mapping.
- The telephone keys map to extensions and the extensions belong to users who are in the same dial plan as the Auto Attendant.
- A public switched telephone network (PSTN) telephone calls Auto Attendant and then selects a key.
- Call-id of the PSTN telephone is blocked.
In this scenario, the call transfer fails.
Note A PSTN caller has anonymous caller-id when the caller-id is blocked. A call transfer only works if the caller selects someone from the Activity Directory. Only a call transfer by using key mapping is broken. However, if OCS 2007 is not involved, there is no problem by using key mapping to transfer a call. In other words, a caller with caller-id blocked can perform a call transfer by using key mapping when a call comes to an Exchange Server 2007 UM server directly from a Private Branch Exchange (PBX) device. Additionally, when this problem occurs, the Exchange Server 2007 UM server sets the caller's address as the following:
sip: anonymous@<domain name>