SIP header manipulation on SBCs

See also

Sources

1. 1
   AudioCodes Mediant 500L (v7.6) cannot manipulate SIP 100 Trying messages or header values longer than 4,096 characters.

   Configuring SIP Message Manipulation - Mediant 500L SBC User's Manual Version 7.6 · Configuring SIP Message Manipulation (restrictions notes) · Checked 2026-10-14
2. 2
   AudioCodes Message Manipulation rules (v7.6) support the action types Add, Remove, Modify, Add Prefix, Add Suffix, Remove Prefix, Remove Suffix and Normalize.

   Configuring SIP Message Manipulation - Mediant 500L SBC User's Manual Version 7.6 · Message Manipulations table > Action Type · Checked 2026-10-14
3. 3
   On hybrid AudioCodes SBC-Gateway devices, when a call is routed from the SBC application to the Gateway application, the device treats the initial SIP message as a new call and ignores manipulations done by the SBC application.

   SIP Message Syntax for Message Manipulation, Message Conditions, Pre-Parsing Manipulation, Call Setup Rules - Reference Guide Version 7.4 · Introduction (hybrid SBC-Gateway note) · Checked 2026-10-14
4. 4
   AudioCodes Mediant 500L (v7.6) supports up to 29 Message Manipulation Sets and up to 100 Message Manipulation rules in total across all sets.

   Configuring SIP Message Manipulation - Mediant 500L SBC User's Manual Version 7.6 · Configuring SIP Message Manipulation (capacity note) · Checked 2026-10-14
5. 5
   On AudioCodes Mediant 500L (v7.6) message manipulation cannot add or remove mandatory headers (To, From, Via, CSeq, Call-ID, Max-Forwards); they can only be modified, and only on dialog-initiating requests.

   Configuring SIP Message Manipulation - Mediant 500L SBC User's Manual Version 7.6 · Configuring SIP Message Manipulation (restrictions notes) · Checked 2026-10-14
6. 6
   AudioCodes Mediant 500 (v7.4) supports up to 10 Pre-Parsing Manipulation Sets and up to 30 pre-parsing rules in total.

   Configuring Pre-Parsing Manipulation Rules - Mediant 500 SBC User's Manual Version 7.4 · Configuring Pre-Parsing Manipulation Rules (capacity note) · Checked 2026-10-14
7. 7
   AudioCodes Pre-Parsing Manipulation (Mediant 500 v7.4) rewrites incoming SIP messages as raw text with regex before parsing, is assigned to a SIP Interface, and runs before pre-classification manipulation and classification.

   Configuring Pre-Parsing Manipulation Rules - Mediant 500 SBC User's Manual Version 7.4 · Configuring Pre-Parsing Manipulation Rules · Checked 2026-10-14
8. 8
   For SBC calls on AudioCodes Mediant 500L (v7.6) inbound message manipulation is done first, then outbound number manipulation, then outbound message manipulation.

   Configuring SIP Message Manipulation - Mediant 500L SBC User's Manual Version 7.6 · Configuring SIP Message Manipulation (processing order) · Checked 2026-10-14
9. 9
   On AudioCodes Mediant 500L (v7.6) inbound and outbound Message Manipulation Sets are assigned to IP Groups, while a pre-classification set is assigned to the SIP Interface for incoming dialog-initiating messages.

   Configuring SIP Message Manipulation - Mediant 500L SBC User's Manual Version 7.6 · Configuring SIP Message Manipulation (assignment) · Checked 2026-10-14
10. 10
    CUBE SIP profiles can be applied at global (all dial-peers), tenant or dial-peer level.

    Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - SIP Profiles · SIP Profiles > applying profiles · Checked 2026-10-14
11. 11
    CUBE SIP profile copy variables u01 to u99 are shared by inbound and outbound SIP profiles, so a value captured inbound can be reused outbound.

    Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - SIP Profiles · SIP Profiles > copy variables · Checked 2026-10-14
12. 12
    Cisco technote 118825 shows CUBE SIP profiles copying a value from the Diversion header into a u01 variable with a regex and reusing it via modify, and removing Diversion with a remove action.

    Use SIP Profiles on CUBE Enterprise Common Use Cases · Common SIP Message Normalization Scenarios > Copy Value from Diversion Header to the From Header; Remove Diversion Header · Checked 2026-10-14
13. 13
    On CUBE, SIP profile rules written for INVITE apply only to the initial INVITE of a call; the REINVITE keyword targets subsequent INVITEs.

    Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - SIP Profiles · SIP Profiles > INVITE and REINVITE rules · Checked 2026-10-14
14. 14
    CUBE applies inbound SIP profile changes before normal call processing, so an inbound profile can change which inbound dial-peer matches.

    Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - SIP Profiles · SIP Profiles > inbound SIP profiles · Checked 2026-10-14
15. 15
    On CUBE the inbound SIP profiles feature must be enabled with sip-profiles inbound under the global voice service voip sip configuration before an inbound profile can be applied.

    Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - SIP Profiles · SIP Profiles > inbound SIP profiles configuration · Checked 2026-10-14
16. 16
    Cisco states that inbound SIP profile modification was introduced after Cisco IOS 15.4 and that IOS 15.3 and earlier support SIP profiles only in the outbound direction.

    Use SIP Profiles on CUBE Enterprise Common Use Cases · Possible Issues · Checked 2026-10-14
17. 17
    On CUBE (IOS XE 17.6 onwards) SIP profiles can modify but cannot add or remove the mandatory SIP headers To, From, Via, CSeq, Call-ID and Max-Forwards.

    Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - SIP Profiles · SIP Profiles > Restrictions · Checked 2026-10-14
18. 18
    CUBE does not perform syntax checking on SIP messages after SIP profile rules have been applied.

    Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - SIP Profiles · SIP Profiles > Restrictions · Checked 2026-10-14
19. 19
    CUBE applies outbound SIP profile manipulation last, after outbound (destination) dial-peer matching.

    Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - SIP Profiles · SIP Profiles > outbound SIP profiles · Checked 2026-10-14
20. 20
    CUBE SIP profiles cannot add or remove entire MIME or SDP bodies, cannot modify image m-line attributes, and apply only to audio and video m-lines.

    Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - SIP Profiles · SIP Profiles > Restrictions · Checked 2026-10-14
21. 21
    CUBE does not increment the SDP o= line version after a SIP profile changes the SDP, which Cisco warns may cause ITSPs to disconnect the call.

    Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - SIP Profiles · SIP Profiles > Restrictions · Checked 2026-10-14
22. 22
    On the Oracle Enterprise SBC an HMR add action places headers at the end of the header list, except Via headers which are added at the top; the index cannot set an insertion position.

    HMR Components - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · Duplicate Header Names · Checked 2026-10-14
23. 23
    Oracle built-in HMRs have names beginning ACME_ (for example ACME_NAT_TO_FROM_IP), are applied through in-manipulationid or out-manipulationid like user HMRs, and are listed with show built-in-sip-manipulation.

    HMR Components - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · Built-In HMRs · Checked 2026-10-14
24. 24
    In B2BUA mode the Oracle Enterprise SBC stores Call-ID values before HMR is applied, so inbound HMR cannot change the Call-ID.

    HMR Fundamentals - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · Applying HMRs to Traffic > Inbound HMR · Checked 2026-10-14
25. 25
    When inbound HMR modifies To, From or Call-ID on an out-of-dialog request, the Oracle Enterprise SBC stores the original header in the dialog and restores it before outbound manipulation without extra rules.

    HMR Components - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · Dialog Matching > Inbound HMR Challenge · Checked 2026-10-14
26. 26
    In OCSBC 8.4.0 the sip-manipulation header-rules action parameter accepts none, add, store, sip-manip, replace, find-replace-all, delete-element, delete-header, log and reject, with default none.

    sip-manipulation > header-rules · header-rules > action · Checked 2026-10-14
27. 27
    Oracle Enterprise SBC applies inbound HMR after parsing the ingress message but before routing, so inbound rules can be used to change routing behaviour.

    HMR Fundamentals - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · Applying HMRs to Traffic > Routing Decisions; Inbound HMR · Checked 2026-10-14
28. 28
    The Oracle Enterprise SBC sip-config option inmanip-before-validate runs inbound HMR before header validation so faulty headers can be repaired, but it cannot repair an invalid first Via and does not apply to responses.

    HMR Components - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · SIP Header Pre-Processing HMR · Checked 2026-10-14
29. 29
    Oracle states the Enterprise SBC does not prevent outbound header manipulation rules from breaking the SIP protocol.

    HMR Fundamentals - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · Applying HMRs to Traffic > Outbound HMR · Checked 2026-10-14
30. 30
    The Oracle HMR msg-type out-of-dialog applies a rule only to requests without a to-tag, and an outbound out-of-dialog rule runs only if the same header rule ran on the dialog-creating request.

    HMR Components - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · Dialog Matching > About Dialog-Matching Header Manipulations; Outbound HMR Challenge · Checked 2026-10-14
31. 31
    Oracle Enterprise SBC applies outbound HMR just before the SIP message is sent, after SIP-NAT processing.

    HMR Fundamentals - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · Applying HMRs to Traffic > Outbound HMR · Checked 2026-10-14
32. 32
    On the Oracle Enterprise SBC a SIP manipulation applied to a session agent overrides one on the realm, and a realm manipulation overrides one on the SIP interface.

    HMR Fundamentals - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · Applying HMRs to Traffic · Checked 2026-10-14
33. 33
    The Oracle HMR reject action rejects matching SIP requests (not responses) with a 4xx, 5xx or 6xx status given as status-code[:reason-phrase], and later rules are not executed.

    HMR Components - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · Rejecting SIP Requests · Checked 2026-10-14
34. 34
    Oracle OCSBC 9.2.0 HMR examples use the find-replace-all action on application/sdp bodies, for example to remove a=ptime lines.

    Configuration Examples · Example 13 Remove a Line from SDP · Checked 2026-10-14
35. 35
    Oracle Enterprise SBC applies header rules in the order entered, so a store rule must be created before any rule that uses its stored value.

    HMR Fundamentals - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · Applying HMRs to Traffic > Order of Header Rule Application · Checked 2026-10-14
36. 36
    Oracle HMR rulesets are stateless across messages: stored strings are usable only within the same ruleset and are forgotten once that ruleset finishes.

    HMR Fundamentals - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · Applying HMRs to Traffic > HMR Store Actions and Boolean Results · Checked 2026-10-14
37. 37
    The Oracle Enterprise SBC cannot validate HMR rules as they are entered; the ACLI verify-config command checks for references to nonexistent rules and circular references.

    HMR Fundamentals - Oracle Enterprise Session Border Controller HMR Guide Release E-CZ8.1.0 · HMR Fundamentals (validation note) · Checked 2026-10-14
38. 38
    RFC 3261 requires implementations to accept both the long and the compact (short) form of each header name, so a manipulation rule keyed only on the long name can miss a header sent in compact form.

    RFC 3261 — SIP: Session Initiation Protocol · Section 7.3.3 Compact Form · Checked 2026-10-14
39. 39
    RFC 3261 defines the dialog ID at each UA as the Call-ID value plus a local tag and a remote tag, so rewriting any of these breaks dialog matching.

    RFC 3261 — SIP: Session Initiation Protocol · Section 12 Dialogs (opening paragraphs) · Checked 2026-10-14
40. 40
    RFC 3261 states that the relative order of header field rows with the same field name is significant.

    RFC 3261 — SIP: Session Initiation Protocol · Section 7.3.1 Header Field Format · Checked 2026-10-14
41. 41
    RFC 3325 allows one or two P-Asserted-Identity values; with two values one must be a sip or sips URI and the other a tel URI.

    RFC 3325: Private Extensions to the Session Initiation Protocol (SIP) for Asserted Identity within Trusted Networks · Section 9.1 · Checked 2026-10-14
42. 42
    RFC 3325 requires a proxy forwarding to an element outside the Trust Domain to remove all P-Asserted-Identity values when the user requested privacy (Privacy: id).

    RFC 3325: Private Extensions to the Session Initiation Protocol (SIP) for Asserted Identity within Trusted Networks · Section 4 Overview; Section 7 Requesting Privacy · Checked 2026-10-14
43. 43
    RFC 5853 states that some forms of topology hiding, such as replacing the Contact header, violate SIP principles.

    RFC 5853: Requirements from Session Initiation Protocol (SIP) Session Border Control (SBC) Deployments · Section 3.1.2 · Checked 2026-10-14
44. 44
    RFC 5853 describes header privacy, the most common form of SBC topology hiding, as stripping Via and Record-Route headers, replacing the Contact header and possibly changing Call-IDs.

    RFC 5853: Requirements from Session Initiation Protocol (SIP) Session Border Control (SBC) Deployments · Section 3.1.1 · Checked 2026-10-14
45. 45
    RFC 5853 states that SBC repair of SDP bodies is incompatible with Authenticated Identity Management and with end-to-end mechanisms such as S/MIME, while header-field repair can be compatible with SIP principles.

    RFC 5853: Requirements from Session Initiation Protocol (SIP) Session Border Control (SBC) Deployments · Section 3.6.2 · Checked 2026-10-14
46. 46
    RFC 7092 states that for a signaling-only B2BUA no SIP header field is guaranteed to be copied from the received request to the generated request.

    RFC 7092: A Taxonomy of Session Initiation Protocol (SIP) Back-to-Back User Agents · Section 3.1.2 · Checked 2026-10-14
47. 47
    RFC 7092 states that SBCs by default typically replace the Contact URI, remove Via and Record-Route, and modify Call-ID, To, From and other headers as well as SDP.

    RFC 7092: A Taxonomy of Session Initiation Protocol (SIP) Back-to-Back User Agents · Section 4.3 · Checked 2026-10-14
48. 48
    Teams Direct Routing requires the Contact header of INVITE and OPTIONS from the paired SBC to carry the SBC FQDN matching its certificate, and refuses a Contact with an IP address hostname with 403 Forbidden.

    Teams Phone System Direct Routing: SIP protocol · Detailed requirements for Contact header and Request-URI > Contact header · Checked 2026-10-14
49. 49
    Microsoft does not support a third-party SIP proxy or UAS between the Microsoft SIP proxy and the paired SBC that might modify the Request-URI created by the paired SBC.

    Teams Phone System Direct Routing: SIP protocol · Processing the incoming request: finding the tenant and user, step 5 · Checked 2026-10-14
50. 50
    Teams Direct Routing requires the phone number in the Request-URI of incoming calls to contain a plus sign, and uses a plus-prefixed From number for blocking and reverse lookup.

    Teams Phone System Direct Routing: SIP protocol · Detailed requirements for Contact header and Request-URI > Request-URI; From Header · Checked 2026-10-14
51. 51
    Across the documented SBCs, rewriting dialog identifiers (Call-ID, From or To tags) is the highest-risk class of header manipulation, because RFC 3261 dialog matching depends on them and vendors either block, restore or silently break such changes.inferred

    RFC 3261 — SIP: Session Initiation Protocol · Section 12 Dialogs; synthesised with Oracle HMR Components Dialog Matching and Ribbon SBC Edge 6.1.x SMM Overview · Checked 2026-10-14

Documents

Cite this page

WarmTransfer. (2026, October 14). SIP header manipulation on SBCs. WarmTransfer. https://warmtransfer.net/knowledge/sbc-header-manipulation

@misc{warmtransfer-sbc-header-manipulation,
  title  = {SIP header manipulation on SBCs},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/sbc-header-manipulation},
  note   = {Verified 2026-10-14}
}