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Vega can relay "User-To-User IE" from SIP INVITE to PRI/ISDN SETUP message and vice versa.

Below contents will describe the required configuration for Vega to send/receive "User-To-User" IE to/from ISDN/SIP.  


Vega needs to have below parameter set in order to pass "XUUI" SIP Header received in SIP INVITE to ISDN SETUP and vice-versa.

"set advanced.sip.q931.tx_tun_mode=xuui" 

NOTE:  Please refer to vega admin guide for further details of "tx_tun_mode" parameter. Here we are focusing only on sending/receiving "XUUI" sip header in INVITE to send/receive User-to-User IE in SETUP.

Sending UUI from SIP to ISDN 

In order to populate "User-to-User" IE in SETUP message , SIP server needs to send below format "XUUI" message in SIP INVITE. 

  X-Uui: protocol-discriminator=4;   OR 


1) Protocol-discriminator will be used to fill "Protocol discriminator" field of 'User-User" IE. This is an optional field.

2) user-information will have data for the "user-information" field of "User-User" IE. 

SETUP message sent by VEGA after getting above X-Uui will looks like as below - 




Sending UUI from SIP to ISDN

VEGA will add "X-UUI" SIP header in outgoing INVITE whenever it received "User-User" IE in incoming SETUP message.

"X-UUI" format will be same as defined while sending the same header from SIP to VEGA.


SIP side wants to send ";encoding=text" so here "@"/";"/"=" needs to be converted into ASCII hex format for vega to recognize these character and send over PRI. 

Original Header Value:;encoding=text

Note: This is what the SIP side wants to send in the User-User IE.

Using the X-Uui Header


Note: The prefix "user-information=" is required including the = sign. Then the "@", ";" and the "=" sign need to be converted to Ascii hex. The changes made to the original value are shown in red. 


Ascii Character To Hex Value

@ -> %40

;   -> %3B

= - > %3D

This will result in the Vega sending the following User-User IE out the PRI. See trace below for example. 


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