Issues with outbound calls - Microsoft Teams

Publisher

Microsoft

URL

https://learn.microsoft.com/en-us/troubleshoot/microsoftteams/phone-system/direct-routing/issues-with-outbound-calls

Published

2023-10-30

Updated

unknown

Accessed

2026-09-25

HTTP status

200

License

Microsoft Learn terms of use; no-redistribution; short excerpts and locators only

Source notes citing this source

• When the far end sees a number other than the one configured, the first thing to check is whether From and P-Asserted-Identity in the outbound INVITE carry different numbers. All three platforms can deliberately split them (Teams substitution with ForwardPai, Unified CM external presentation, Webex Dual Identity), and at least one vendor documents carriers preferring PAI. inferred in context
• In Direct Routing, Microsoft's troubleshooting article says the From header holds the caller's number (or 'anonymous'), a substitute number from CsCallingLineIdentity, or the original caller's number on a forwarded call, while P-Asserted-Identity holds the number of the user billed for the call. in context
• Microsoft attributes a wrong caller ID on Direct Routing calls to From and P-Asserted-Identity differing while the PSTN prioritizes PAI, and recommends configuring the SBC to remove or modify the PAI header. in context
• Microsoft's outbound-call article says that when Teams calls reach the SBC but fail with SIP 403 or 404, the PSTN provider is the most likely source, and you should contact the provider. in context
• If no user in a tenant can make outbound calls, Microsoft suggests two checks. First, whether the gateway is disabled: Get-CsOnlinePSTNGateway should show Enabled True, and it can be fixed with Set-CsOnlinePSTNGateway -Enabled $true. Second, whether a firewall is blocking SIP OPTIONS from the Microsoft signaling IPs and FQDNs. in context
• Pasting into an Online Voice Routing Policy from Word or another WYSIWYG editor can insert invisible characters that still affect route selection. Microsoft's fix is to remove the policy and recreate it by typing it or pasting from a plain-text editor. in context

Cite this source record

APA

WarmTransfer. (2023, October 30). Issues with outbound calls - Microsoft Teams. WarmTransfer. https://warmtransfer.net/knowledge/sources/ms-learn-dr-outbound-call-issues

BibTeX

@misc{warmtransfer-ms-learn-dr-outbound-call-issues,
  title  = {Issues with outbound calls - Microsoft Teams},
  author = {{WarmTransfer}},
  year   = {2023},
  url    = {https://warmtransfer.net/knowledge/sources/ms-learn-dr-outbound-call-issues},
  note   = {Microsoft, accessed 2026-09-25}
}