Have the CUCM 6.x integrated with Cisco Unity 5.x via SCCP.
The incoming call's flow consists of several discrete steps.
1.1 External incoming call comes to the CUCM via voice gateway VGW-1.
1.2 Call Setup has ANI=1234567 and DNIS=1111.
2. There is the 'CTI Route Point' configured on CUCM with DN=1111.
3. DN=1111 has checkbox 'CFA to VoiceMail' enabled.
4. Call is forwarded to first available registered VM port; this port has DN=100.
5. Then incoming call connected with the AA call handler on Cisco Unity.
6.1 AA, as usual, allows caller to transfer themselves to internal extensions by dialing additional DTMF.
6.2 Caller dial extra digits (let it be 2222) and Unity returns these dialed digits to CUCM for matching.
7. CUCM also has 'Route Pattern'=2222 pointing to specific PRI on MGCP-controlled voice gateway VGW-2.
After enabling 'debug isdn q931' on VGW-2 I see ISDN call Setup where ANI=100 and DNIS=2222.
This call setup is received by specialized conferencing hardware which must obtain "correct",
id est s_o_u_r_c_e, ANI to provide different class of conferencing services for external callers.
In the absence of original ANI this task's completion is not possible.
How and what/where should I check/configure on CUCM/Unity to allow ANI=1234567 to pass untouched towards to CFR hardware.
You need to set Display Original Calling Number on Transfer from Cisco Unity to True. This will allow the number from which the call came from to pass even one the call is coming from Unity. By default this is disabled and only the VM port is displayed.
This parameter is located in Service Parameter of Call manager.
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