PSTN rejecting Call Fwd calls due to Redirecting Number

[billmatthews]

We have a CUCM 10.5 environment.  Our internal phones have four digit extensions.  CUCM has a SIP trunk to our CUBE, which has a PRI to our PSTN.  Inbound/Outbound calling works fine.  For outbound calls we use an external mask on the line.

However, when a user applies a Call Fwd All to their line, our PSTN is rejecting it.  I did a debug, and it reached the CUBE, but the PSTN disconnects the call.  The calling and called party are correct, and the PSTN allows that call when it's a direct call.  But on the Call Fwd All, I see it adds Redirecting Number, which exposes our internal four digit extension.  

How can I hide that from the PSTN? Debug below.

Thanks!

000686: Dec  2 22:12:35.404: ISDN Se0/0/0:23 Q931: Applying typeplan for sw-type 0xD is 0x2 0x1, Calling num 3105867434
000687: Dec  2 22:12:35.404: ISDN Se0/0/0:23 Q931: Sending SETUP  callref = 0x0098 callID = 0x8019 switch = primary-ni interface = User
000688: Dec  2 22:12:35.404: ISDN Se0/0/0:23 Q931: TX -> SETUP pd = 8  callref = 0x0098
        Bearer Capability i = 0x8090A2
                Standard = CCITT
                Transfer Capability = Speech
                Transfer Mode = Circuit
                Transfer Rate = 64 kbit/s
        Channel ID i = 0xA9838D
                Exclusive, Channel 13
        Calling Party Number i = 0x2181, '3105867434'
                Plan:ISDN, Type:National
        Called Party Number i = 0xA1, '3102440186'
                Plan:ISDN, Type:National
        Redirecting Number i = 0x00018F, '8099'
                Plan:Unknown, Type:Unknown
        Calling Party Number i = 0x2181, '3105867434'
                Plan:ISDN, Type:National
        Called Party Number i = 0xA1, '3102440186'
                Plan:ISDN, Type:National

[Suresh Subramanian · Accepted solution]

uncheck the Redirecting Diversion Header Delivery - Outbound  in the CUCM SIP Trunk configuration and check the calls please

[Garrett Hensley]

I have the same issue and unchecking that box does indeed remove the redirecting number information from the isdn setup messages. My question is what would the PSTN use this information for if I did want to pass it? I have found that the PSTN will accept a redirecting number if it is one of the numbers assigned to the PRI.