In this post I like to highlight the availability to SIP gateway for Microsoft Teams. Microsoft announced the SIP gateway for compatible phones as general available in a recent Teams Blog post. This new service added and extending the Teams calling service to attach compatible SIP phones to your telephony deployment based on Microsoft Teams. In the following paragraphs I sum up the key aspects of the SIP gateway. Hereinafter, I do not explain Teams PSTN calling options.

Microsoft Teams SIP gateway
Microsoft Teams SIP gateway

Available features for compatible SIP phones [16.12.2021]

By the time of writing this article the following features are mentioned in the documentation to be supported:

  • Make and receive calls
  • Hold and resume
  • Mute and unmute
  • Multiple simultaneous calls by using hold and three-party confernce call
  • DTMF (Dual-tone multi-frequency)
  • Teams meetings dialin
  • Cold call transfer
  • Consultative call transfer
  • Local call forwarding
  • Listen to voicemail
  • Message waiting indicator (MWI)
  • Do not disturb only for the SIP phone
  • User sign-in/-out
  • Skype for Business phones which connect via a third-party gateway can use the SIP gateway beyond 2023

Requirements

In case a sip phone should be used the Teams users must have a phone number with PTSN calling and a suited licenses assigned (e.g. E1, phone system license for Direct Routing or else).

The Teams calling policy must be enabled for SIP phones and assigned to the users for SIP phones.

Source: Teams Admin Center – Calling Policy

Moreover, your IT infrastructure must allow SIP phone traffic as well (firewall, proxy, …).

Configuration

I’m not going to explain the configuration here, because it is very well documented on Configure SIP Gateway – Microsoft Teams | Microsoft Docs.

Administration and monitoring

SIP phones can be monitored and administered to a certain extend via Teams Admin Center.

Source: Teams Admin Center – Devices -SIP devices

Conclusion, opinion and summary

SIP gateway for Microsoft Teams Voice deployments are a good opportunity to simplify the deployment because you do not need to deploy your own one or connect all SIP phones to a SBC. Furthermore you could keep existing legacy SIP phones, if compatible.

As of now there is no support for analog device gateways to register analog endpoints via the analog device gateway like a SIP endpoint, e.g. in case of Teams Calling Plans and the need for a few analogs like a doorbell or fax machine. But one step after another.

Additional resources