Microsoft does not support a third-party SIP proxy or user agent server between the Microsoft SIP proxy and the paired SBC that might modify the Request-URI created by the SBC.

Checked 2026-09-25

Vendor
Microsoft
Product
Teams Phone Direct Routing
Subsystem
SIP signaling
Deployment
multi-tenant, hybrid
Region
not restricted
Release range
current as of 2026-09-25
Checked
2026-09-25

Sources

Cite this note

APA

WarmTransfer. (2026, September 25). SIP ALG problems on firewalls and routers: source note sip-alg-problems-teams-dr-no-modifying-proxy. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-alg-problems-teams-dr-no-modifying-proxy

BibTeX

@misc{warmtransfer-claim-sip-alg-problems-teams-dr-no-modifying-proxy,
  title  = {SIP ALG problems on firewalls and routers: source note sip-alg-problems-teams-dr-no-modifying-proxy},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/sip-alg-problems-teams-dr-no-modifying-proxy},
  note   = {Source note sip-alg-problems-teams-dr-no-modifying-proxy, checked 2026-09-25}
}

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