Erwin Bierens

Knowledge is Power

Microsoft Teams - Direct Routing Root Certificates Update

2022-10-05 1 min read Microsoft Teams

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

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

2021-02-24 2 min read Audiocodes Microsoft Teams
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

2020-12-03 2 min read Audiocodes Microsoft Teams
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

Microsoft Teams Direct Routing IP Addresses

2020-10-21 2 min read Microsoft Teams
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

Direct Routing keeps sending Anonymous

2020-10-05 1 min read Microsoft Teams
Problem While i was configuring an Audiocdes SBC with Direct Routing setup and started testing, we faced the issue that every call outgoing is presenting Anonymous as caller ID. When looking up the SDP invite i saw the parameter Privacy showing up. Solution After some digging, i found that the Privacy ID is added automatically when you enable the option -forwardPAI $true (P-Asserted-Identity) within the Set-CsOnlinePSTNGateway cmdlet. Because i don’t want to remove the PAI, i created the following manipulation rule in the Audiocodes SBC to remove the Privacy ID. Continue reading
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