Microsoft365 has been gaining tremendous traction over the last few years. With Microsoft Teams as a component of Microsoft365, it too, has seen adoption as a collaboration solution for companies of all sizes. As these solutions become ubiquitous, Microsoft Teams has also become an option to replace legacy telephony solutions.

There are three primary options for bringing Public Switched Telephone Network (PSTN) connectivity to Microsoft Team. These include Calling Plans from Microsoft, Direct Routing, and Operator Connect.

What is Microsoft Teams Phone with Calling Plan?

Microsoft Teams Phone with Calling Plan (aka Microsoft Calling Plan) is Microsoft’s PSTN service to bring phone services to Microsoft Teams. Microsoft becomes your phone carrier. Microsoft offers both domestic and international plans to meet customer requirements.


  • Microsoft Calling Plan is designed to be a simple, self-service, all-in-one solution.
  • You can use your existing phone numbers by porting them to Microsoft.
  • ‘Communication Credits’ can be added to account for overages of plan minutes, Toll Free inbound calls, and International Calling to name a few.


  • Calling Plans are not available in all countries.
  • Using Calling Plans can be more expensive than other options. (Direct Routing, Operator Connect)
  • Number Porting is ‘self-directed’ and prone to challenges.

Note: If you have more advanced requirements, Calling Plans may be too limiting for your needs.

What is Direct Routing?

Direct Routing allows for the use of the PSTN carrier of your choice. Providers of Direct Routing services like Altigen, are experts in telephony solutions and assist in planning, deployment, and support of your Teams Phone solution. Again, both domestic and international calling options are available.


  • International dialing is available in almost every country.
  • Experts can simplify the number porting process and know the intricate process of working with other carriers to make the transition seamless.
  • Porting numbers is a guided process with most Direct Routing providers including ensuring there is no ‘downtime’ during the porting process.
  • Direct Routing plans can be significantly less expensive when compared to Microsoft Calling Plans.
  • Direct Routing solutions can support more complex environments.


  • Set up and configuration can be more complicated than Microsoft Calling Plans, unless you choose a Direct Routing provider wisely.
  • Selection of a Direct Routing provider is a critical decision.

What is Operator Connect?

Operator Connect is a new option to bring PSTN to your Microsoft Teams environment. This solution is still in ‘Public Preview’, at the time writing. This means Microsoft allows early access to select carriers who can test the solution and features prior to General Availability (GA).

Next Steps

Moving to Microsoft Teams Phone System can be a complicated decision with many considerations needed to make a solid decision.

  1. Analyze your requirements to determine if and how Microsoft Teams can replace your legacy phone system.
  2. Determine the right solution for PSTN connectivity. Is Teams Phone system or a Direct Routing solution financially beneficial.
  3. Ensure your Direct Routing provider is qualified including:
    • Is their Direct Routing solution certified by Microsoft?
    • Are they a Gold Microsoft Partner?
    • Does the provider offer the services and solutions to meet your requirements?

Where do I start?
Contact Altigen Communications Today for a free consultation with an expert!
Phone: +1-408-597-9000
Website: Atigen Direct Routing Solution

Altigen Direct Routing provides a secure, high-quality SIP-based voice services for Microsoft Teams Phone System. Our SIP trunks are connected to Microsoft Teams via managed SBC’s deployed in Azure as a Microsoft Certified Solution.