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“484 Address Incomplete” on outbound calls when using Microsoft Teams Direct Routing

Over the past few weeks I have setup Microsoft Teams Direct Routing on Ribbon SBCs in a number of countries all over the world. On a few occasions I have run into a“484 Address Incomplete” issue when making outbound calls from Microsoft Teams.

It would appear that some carriers don’t like the P-Asserted-Identity that is applied when the call leaves Microsoft. The solution is to strip the P-Asserted-Identity SIP header just before it leaves the SBC as it heads towards the carrier.

Example of the SIP 484 error:

Received From 10.200.1.210:5060 On 10.200.1.200:5060 via UDPCALL-ID: call-1BE92823-0000-0010-021E-104B@10.200.1.200
GCID: 4174
Message found at line: 5892
SIP/2.0 484 Address Incomplete
Via: SIP/2.0/UDP 10.200.1.200:5060;branch=z9hG4bK-UX-0a42-07da-87965
Record-Route: <sip:10.200.1.210:5060;transport=udp;lr>
Call-ID: call-1BE92823-0000-0010-021E-104B@10.200.1.200
From: "Microsoft Teams DR Test"<sip:2222222@10.200.1.200:5060;user=phone>;tag=a4207da-82027;sgid=2
To: <sip:0044xxxxxxxxxx@10.200.1.210:5060;user=phone>;tag=sbc04e22ac
CSeq: 2 INVITE
Reason: Q.850;cause=28;text="address incomplete"Content-Length: 0

If we look at the P-Asserted-Identity in the SIP INVITE from the SBC to the carrier we see the following:

P-Asserted-Identity: "Microsoft Teams DR Test" <sip:+XXXXXXXXXXXX@sbc.yourdomain.com:5061;user=phone>

This is the P-Asserted-Identity inserted by Microsoft and it seems like some carriers just don’t like it. I’ve seen this with two carriers in India and one in the Middle East so far.

In order to get around this we need to use message manipulation to remove the PAI SIP header before it gets to the carrier.

Create & Apply Message Manipulation

Under Settings > SIP > Message Manipulation > Message Rule Tables create a new table called something like “Remove PAI”

Under your new Message Rule Table create a new Header Rule called something like “Remove PAI”:

Apply this message table to the Inbound Message Manipulation list on your signaling group for Microsoft Teams (or for your Proxy SBC if this is a downstream SBC).

To apply this, go to your signaling group, scroll to the bottom and set Message Manipulation to “Enabled”. Once done, choose your “Remove PAI” message table in the Inbound Message Manipulation section.

Once done, the P-Asserted-Identity in the working SIP INVITE will be different that it was previously:

P-Asserted-Identity: "Microsoft Teams DR Test" <sip:XXXXXXX@10.xx.xx.xx:5060;user=phone>

Job done.

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Matt Ellis

Matt Ellis

Unified Communications Architect, Pompey fan, burger eater, coffee drinker...

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