Microsoft Teams Direct Routing IP Addresses

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.pstnhub.microsoft.com

The first one will be located by location and performance metrics. If your location is EMEA, you 2nd location will be US and the 3th ASIA.

Microsoft Teams - Direct Routing Root Certificates Update

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.

Audiocodes - Block spam calls

More and more we hear customers complaining about spam likely calls, There is a way to block these calls based on your dialplan and an IP-2-IP route in the Audiocodes Mediant SBC.

DialPlan

If you are not using the DialPlan you will need to create one first, if you already use a DialPlan we can reuse it.

Navigate to Signalling & Media > SIP Definitions > DialPlan

Click on DialPlan Rule X items > Add a new DialPlan Rule > New

Review: Audiocodes C470HD

This post is a long time coming. I’ve had this phone for quite some while placed on my desk. I’m not a big fan of desk phones because i want to work from anyplace / anywhere, but in this particular i was very interested in the Audiocodes C470HD because it has WiFi onboard.

If you’re reading this, you are probably already familiar with AudioCodes. I was first introduced to them when I was installing Lync for a customer and needed a qualified gateway. AudioCodes, in fact, has a huge list of products for Microsoft Teams / Skype for Business from physical and virtual SBCs, gateways and VoIP, IP Phones and AI solutions.

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. This way you can migrate your users in steps to Microsoft Teams.

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@20:11:36.770]
            20:11:35.145  172.20.1.1  local0.warn    [S=3603725] [SID=815d0e:57:143476]  (N  3305190)!! [ERROR] (#430)RTS::AllocateResource Allocate Resource - cannot allocate DSP. probably lack of resources [Time:23-11@20:11:36.770]

When i look in to my license i have transcoding assigned by the OVOC, but they are not allocated:

Upgrading the Audiocodes One Voice Operations Center (OVOC)

AudioCodes One Voice Operations Center (OVOC, also known as Element Management System and IP Phone Manager) is a web-based voice network management solution that combines management of voice network devices (Audiocodes IP Phones, Mediapacks, Mediants etc..) and quality of experience monitoring into a single, intuitive web-based application.

OVOC enables administrators to manage and to adopt a holistic approach to network lifecycle management by simplifying everyday tasks and assisting in troubleshooting all the way from detection to correction.