Where's my Caller-ID Calling Name Man? (PRI Inbound Calling Name in subsequent FACILITY)

It's been a long minute since I've run into this particular scenario.  Unfortunately, I didn't have the solution in my notes so I reached out to my old pal google for some inspiration.

We just had a new telco company install a voice PRI with the intention of replacing our existing telco company's PRI at one of our remote sites.  After installing and testing the new voice PRI we realized that the inbound calling name was not displayed on the phones.

In this particular scenario the setup looked something like this:

PRI -----ISDN-----> Cisco ISR-G2 VG -----SIP-----> CUCM -----SCCP-----> Cisco IP Phone

We ran a "debug isdn q931" to troubleshoot the problem.  Upon inspection we found that the calling party name was not being sent in the initial ISDN setup message.  In fact, it indicated that the calling name would be send in a "subsequent FACILITY message".

First, the voice gateway won't process the calling name in a subsequent Facility messages by default. The fix for that is to apply the following to the d channel of the PRI:

interface Serial X/X/X:23
 isdn supp-service name calling

Secondly, there is a problem in this scenario with the voice gateway sending a SIP invite to Communications Manager right after it gets the ISDN setup message.  Since the initial ISDN setup message doesn't have the calling name the SIP invite will also be lacking the calling name. When we tested at this point the phones were showing "From pending" as the calling name. The work around for this issue is to introduce a delay before the voice gateway sends the SIP invite to CUCM. Each scenario may require a different amount of time. One can look at the debugs to find out how long it takes between the time the initial ISDN setup message is received and when the ISDN facility message with the name is received. In this particular case we tuned the delay to 500 milliseconds and it seems to work well. The command to delay the setup for 500 milliseconds is.

sip-ua
 timers buffer-invite 500

For more information, Cisco also has a bug id CSCup91440 that references using a buffer-invite on individual dial peers.

Below are some samples of what the debugs looked like on a typical inbound telco call and the telco that sends the calling name in a later message.

Standard Telco "Before Debug"
(The actual telephone numbers have been changed to protect the innocent.)

507963: Jan 22 09:53:13.269: ISDN Se0/2/0:23 Q931: RX <- SETUP pd = 8  callref = 0x14D4
        Bearer Capability i = 0x8090A2
                Standard = CCITT
                Transfer Capability = Speech 
                Transfer Mode = Circuit
                Transfer Rate = 64 kbit/s
        Channel ID i = 0xA98382
                Exclusive, Channel 2
        Facility i = 0x9F8B0100A11702010D020100800F4368696361676F202020202020494C
                Protocol Profile =  Networking Extensions
                0xA11702010D020100800F4368696361676F202020202020494C
                Component = Invoke component
                        Invoke Id = 13
                        Operation = CallingName
                                Name Presentation Allowed Extended
                                Name = Joshua Learn
        Display i = 'Joshua Learn'
        Calling Party Number i = 0x2180, '8005551212'
                Plan:ISDN, Type:National
        Called Party Number i = 0x80, '8885551212'
                Plan:ISDN, Type:National
507964: Jan 22 09:53:13.269: ISDN Se0/2/0:23 Q931: Received SETUP  callref = 0x94D4 callID = 0x13E4 switch = primary-ni interface = User 


Subsequent Facility Message Telco "After"
(The actual telephone numbers have been changed to protect the innocent.)

040306: Jan 22 07:49:27.801 PST: ISDN Se0/2/0:23 Q931: RX <- SETUP pd = 8  callref = 0x1A22
        Bearer Capability i = 0x8090A2
                Standard = CCITT
                Transfer Capability = Speech
                Transfer Mode = Circuit
                Transfer Rate = 64 kbit/s
        Channel ID i = 0xA98381
                Exclusive, Channel 1
        Facility i = 0x9F8B0100A10F02016A06072A8648CE1500040A0100
                Protocol Profile =  Networking Extensions
                0xA10F02016A06072A8648CE1500040A0100
                Component = Invoke component
                        Invoke Id = 106
                        Operation = InformationFollowing (calling_name)
                                Name information in subsequent FACILITY message
        Progress Ind i = 0x8281 - Call not end-to-end ISDN, may have in-band info
        Calling Party Number i = 0x2183, '8005551212'
                Plan:ISDN, Type:National
        Called Party Number i = 0xA1, '8885551212'
                Plan:ISDN, Type:National
040307: Jan 22 07:49:27.801 PST: ISDN Se0/2/0:23 Q931: Received SETUP  callref = 0x9A22 callID = 0x1D81 switch = primary-ni interface = User
040308: Jan 22 07:49:27.805 PST: ISDN Se0/2/0:23 Q931: TX -> CALL_PROC pd = 8  callref = 0x9A22
        Channel ID i = 0xA98381
                Exclusive, Channel 1
040309: Jan 22 07:49:27.848 PST: ISDN Se0/2/0:23 Q931: RX <- FACILITY pd = 8  callref = 0x1A22
        Facility i = 0x9F8B0100A11702016B020100800F332054524143452020202020202020
                Protocol Profile =  Networking Extensions
                0xA11702016B020100800F332054524143452020202020202020
                Component = Invoke component
                        Invoke Id = 107
                        Operation = CallingName
                                Name Presentation Allowed Extended
                                Name = Joshua Learn