If the SBC advertises REFER in its Allow header, the Direct Routing SIP proxy sends REFER to the SBC and acts as Transferor (RFC 5589 section 6). Otherwise the proxy terminates the client's REFER itself and acts as Referee.

Checked 2026-09-23

Vendor
Microsoft
Product
Teams Phone Direct Routing
Subsystem
call-transfer
Deployment
multi-tenant
Region
not restricted
Release range
current as of 2026-09-23
Checked
2026-09-23

Sources

Cite this note

APA

WarmTransfer. (2026, September 23). Teams Phone Direct Routing and SBC certification: source note teams-direct-routing-refer-method-selection. WarmTransfer. https://warmtransfer.net/knowledge/claims/teams-direct-routing-refer-method-selection

BibTeX

@misc{warmtransfer-claim-teams-direct-routing-refer-method-selection,
  title  = {Teams Phone Direct Routing and SBC certification: source note teams-direct-routing-refer-method-selection},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/teams-direct-routing-refer-method-selection},
  note   = {Source note teams-direct-routing-refer-method-selection, checked 2026-09-23}
}

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