Erwin Bierens

Knowledge is Power

Unlock the Full Potential of Microsoft Teams with Direct Routing: A Complete Guide

2023-01-31 3 min read Microsoft Teams     "Erwin Bierens"

Microsoft Teams has become the go-to platform for communication and collaboration, but did you know that you can enhance its functionality even further with Direct Routing? Direct Routing allows you to integrate Teams with your existing telephony system (PABX), giving you access to advanced call and voicemail features, and enabling seamless communication both inside and outside your organization.

In this blog post, we’ll explore what Direct Routing is, why it’s essential for your business, and how you can set it up.

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Microsoft Teams Direct Routing IP Addresses

2023-01-03 2 min read Microsoft Teams     "Erwin Bierens"
When using your own SIP Trunk (BYOT) in combination with a SBC to setup Direct Routing to Microsoft Teams you will need to make some firewall rules. You can find the up to date IP addresses in belows chapters. This will only be for Microsoft 365, Office 365, and Office 365 GCC tenants. Signaling IPs When configuring Direct Routing you will need to setup 3 FQDNs for signaling. sip.pstnhub.microsoft.com sip2.pstnhub.microsoft.com sip3. Continue reading

Microsoft Teams - Direct Routing Root Certificates Update

2022-10-05 1 min read Microsoft Teams     "Erwin Bierens"

On May 12, 2025, the current root certificate “Baltimore CyberTrust Root” expires. This certificate now handles the encryption of Microsoft Teams but also Azure Communication Services and even still the old Skype for Business Online components.

The transition to the new root certificates has started by Microsoft in January 2022 and will be completed this month, October 2022. In case you are using Direct Routing with your Microsoft 365 tenant you probaly have uploaded the Baltimore CyberTrust Root certificate in to your SBC.

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Microsoft Teams - Using the SIP Gatway

2022-06-13 3 min read Microsoft Teams     "Erwin Bierens"

While native Microsoft Teams phone devices provide the complete Teams user experience, we still met customers with an bunch of legacy SIP devices. In order to help these customers with their migration to Microsoft Teams, Microsoft has launched the Teams SIP Gateway. This is a cloud service that enables core Teams calling functionality on compatible SIP phone models from Cisco, Poly, Yealink and AudioCodes.

I’m going to describe the steps on how to provision SIP phones for Teams calling using this SIP Gateway with a Cisco CP-7841 IP Phone.

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Setting up tag based routing in Audiocodes Mediant

In this post i want to show the configuration steps of configuring tag based routing. You can use Dial Plan tags for determining the destination (IP Group) of an IP-to-IP Routing rule. One of the advantages of using Dial Plan tags is that it can reduce the number of IP-to-IP Routing rules that you would normally need to configure. For example: When you have an SBC with SIP trunk and legacy PBX and you would like to implement Microsoft Teams Direct Routing you can route specific numbers to Teams and the rest goes automatically to the legacy PBX. Continue reading

Transcoding issue on the Audiocodes Mediant

I have had a issue with a customer where we have implemented Direct Routing. It’s a HA setup version 7.20A.260.095 running virtual on a VMware cluster. The alarm says: License Pool Alarm. Some of the license pool allocations exceed maximum capability and will not be applied. In the syslog i see the followig errors show up: 20:11:35.145 172.20.1.1 local0.warn [S=3603724] [SID=815d0e:57:143476] (N 3305189)!! [ERROR] ResourceCounter: Cannot allocate more Media channel [0/0] [Time:23-11@20:11:36. Continue reading
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