Microsoft response code 531052 with SIP 488 ('Cannot negotiate a new modality with blackhole media') means the SBC sent SDP with connection address 0.0.0.0, which the Microsoft SIP stack doesn't support.

Checked 2026-09-25

Vendor
Microsoft
Product
Microsoft Teams Phone Direct Routing
Subsystem
sip-response-codes
Deployment
multi-tenant
Region
not restricted
Release range
current as of 2026-09-25
Checked
2026-09-25

Sources

Cite this note

APA

WarmTransfer. (2026, September 25). Troubleshooting Teams Direct Routing: source note teams-direct-routing-troubleshooting-488-blackhole. WarmTransfer. https://warmtransfer.net/knowledge/claims/teams-direct-routing-troubleshooting-488-blackhole

BibTeX

@misc{warmtransfer-claim-teams-direct-routing-troubleshooting-488-blackhole,
  title  = {Troubleshooting Teams Direct Routing: source note teams-direct-routing-troubleshooting-488-blackhole},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/teams-direct-routing-troubleshooting-488-blackhole},
  note   = {Source note teams-direct-routing-troubleshooting-488-blackhole, checked 2026-09-25}
}

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