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Known limitations in Azure telephony

This article provides information about limitations and known issues related to telephony in Azure Communication Services.

Azure Communication Services direct routing known limitations

  • Maximum number of configured Session Border Controllers (SBC) is 250 per communication resource.
  • When you change direct routing configuration (add SBC, change Voice Route, etc.), wait approximately five minutes for changes to take effect.
  • If you move SBC FQDN to another Communication resource, wait approximately an hour, or restart SBC to force configuration change.
  • Azure Communication Services SBC Fully Qualified Domain Name (FQDN) must be different from Teams Direct Routing SBC FQDN.
  • One SBC FQDN can be connected to a single resource only. Unique SBC FQDNs are required for pairing to different resources.
  • Media bypass/optimization isn't supported.
  • Azure Communication Services direct routing isn't available in Government Clouds.
  • Multitenant trunks aren't supported.
  • Location-based routing isn't supported.
  • No quality dashboard is available for customers.
  • Enhanced 911 isn't supported.
  • In-band Dual-tone multi-frequency (DTMF) isn't supported. Use RFC 2833 DTMF instead.
  • Multiple IP addresses mapped with the same FQDN on the SBC side aren't supported.
  • Maximum call duration is 30 hours.
  • Early media isn't supported for group calls.

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