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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.

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   borderStyle none
   Caption 0 Figure 1 Create SIP Header Rule Image Modified

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.

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   borderStyle none
   Caption 0 Figure 1 Create SIP Raw Message Rule Image Modified

3. The resulting SMM table. Make sure to apply the SMM Table to the egress Signaling Group.

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   borderStyle none
   Caption 0 Figure 1 User to User Image Modified

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