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This document assumes the user has a working knowledge of the SBC, its WebUI and the SMM function.

Summary

When adding a custom SIP header, the case of letters in the added header is not preserved. To restore the proper case, a second SMM entry, using the Raw Rule, is needed.

Input Invite

INVITE sip:6001@10.1.24.57:5060;user=phone SIP/2.0

user-to-user: 04412C312C49412C696476313130302C49445F552C41522C2C2C2C4E2C4E2C4E6F6E652C;encoding=hex
Allow: INVITE, ACK, CANCEL, BYE, UPDATE, NOTIFY, OPTIONS, REFER, REGISTER
Call-ID: call-8AA25A00-0000-0010-0C13-29@10.1.24.37
Contact: <sip:07768200610@10.1.24.37:5060;transport=UDP>
Content-Length: 263
Content-Type: application/sdp
CSeq: 1 INVITE
From: <sip:07768200610@10.1.24.37:5060>;tag=c0a8e61b-61
Max-Forwards: 70
P-Asserted-Identity: <sip:07768200610@10.1.24.37:5060>
Referred-By: <sip:33333@10.1.24.80;transport=tcp>
Supported: replaces,update,100rel
To: <sip:6001@10.1.24.57:5060;user=phone>
User-Agent: NET UX 2.2.1v195 UX
Via: SIP/2.0/UDP 10.1.24.37:5060;branch=z9hG4bK-UX-c0a8-e61b-0439

Configuring SMM to Restore Upper-Case Letters

  1. Create a Header Rule that adds the User-to-User header and populates it with the value stored in SG User Value 1. SG User Value 1 would have been populated using a different SMM rule at the ingress SG.

    Create SIP Header Rule

  2. When the SBC creates the new header, the case of the letters is not preserved (all the upper-case letters are sent as lower-case). To re-establish the proper case, make a second entry in the SMM table - a Raw Rule. Set the regex input to the lower-case and the regex output to the desired case. The Raw Rule will restore the desired case.

    Create SIP Raw Message Rule


     

  3. Apply the SMM Table to the egress Signaling Group.

Output Invite

INVITE sip:6001@10.1.24.57:5060;user=phone SIP/2.0
User-to-User: 04412C312C49412C696476313130302C49445F552C41522C2C2C2C4E2C4E2C4E6F6E652C;encoding=hex
Allow: INVITE, ACK, CANCEL, BYE, UPDATE, NOTIFY, OPTIONS, REFER, REGISTER
Call-ID: call-8AA25A00-0000-0010-0C13-29@10.1.24.37
Contact: <sip:07768200610@10.1.24.37:5060;transport=UDP>
Content-Length: 0
Content-Type: application/sdp
CSeq: 1 INVITE
From: <sip:07768200610@10.1.24.37:5060>;tag=c0a8e61b-61
Max-Forwards: 70
P-Asserted-Identity: <sip:07768200610@10.1.24.37:5060>
Referred-By: <sip:33333@10.1.24.80;transport=tcp>
Supported: replaces,update,100rel
To: <sip:6001@10.1.24.57:5060;user=phone>
User-Agent: NET UX 2.2.1v195 UX
Via: SIP/2.0/UDP 10.1.24.37:5060;branch=z9hG4bK-UX-c0a8-e61b-0439

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