Direct Routing and call transfers/parks failing

New Contributor

We have a Ribbon SBC hosted in the cloud, and nothing has changed. It's been working flawlessly for several months, and today my SBC as well as a few clients can no longer transfer or park calls. Logs are showing "SIP/2.0 480 Temporarily Not Available" when we try to transfer a call. 


Anyone else getting this issue today? Like I said, we've made no changes to either SBC. 

21 Replies
I'm also having similar issues today. No changes, Ribbon SBC. getting a 500, internal server error from Teams. Transfers and call park fails.

Any workaround or resolution?


We are having the same issue.  We opened a ticket with Microsoft and have gathered everything they have asked for and are still waiting for a resolution.

@PhoneGuy @BrianC614 We are using an Azure hosted version of Ribbon SWe Lite. Are you 2 using an on-prem/azure hosted SBC? Or are you on Ribbon Connect? Have either of you contacted Ribbon Support yet? We are planning to call them shortly.

2x Azure Hosted Ribbon SBC SWe Edge (formerly known as SWe lite) 11.0.0. Literally no changes to the SBC, so it has to be a change on the Microsoft side. The SBCs don't update/change themselves! Have not contacted Ribbon, waiting on Microsoft to provide some direction, as it doesn't make sense for it to be a Ribbon issue.
Thanks Brian. I'm going to call Ribbon for us and have them look at the logs. Maybe they'll be able to confirm it's a Microsoft issue or point us in the right direction.

@BrianC614  Agreed, I do think it's likely something Microsoft changed or it could be an issue on their side they are unaware of. My fear is they changed something on their end permanently that we now need to adapt our configuration to. @RDub2k4 and I work together so we are just trying to get this hashed out because it's affecting clients of ours as well as our own office. We will keep this thread updated with any new findings. If you wouldn't mind updating us if you learn anything new it would be much appreciated!

I agree. Microsoft support is already trying to blame Ribbon without even looking into what may have changed on their side. They are stating that the Ribbon SBC is sending a 503 service unavailable, which is true, but the question is what changed on Microsoft's side to cause that response? Really appreciate any feedback you get from Ribbon.
Waiting to hear back from Ribbon. I sent the logs and our configuration. We're getting the 500 Internal Server Error as well now. Edited our phone # and domain/IP out.

SIP/2.0 500 Internal Server Error
FROM: <sip:+Email address removed:5061;user=phone>;tag=afb0104-2ccf13;sgid=1
TO: <>;tag=bec5e1dda8c24ca2b3a91f1e9e1e9f20
CALL-ID: Email address removed.X
VIA: SIP/2.0/TLS XX.XXX.XXX.X:5061;branch=z9hG4bK-UX-0afb-0104-31a078
REASON: Q.850;cause=47;text="4b4590df-0515-49bc-9f78-253a3990c28a;Call notification"
SERVER: Microsoft.PSTNHub.SIPProxy v.2022.4.4.11 i.EUNO.12
@BrianC614 @PhoneGuy Check this out, especially the area titled "Replace headers"
I bet that's our issue.
Thanks @jsnider ! Any idea where to look for that in the Ribbon SBC config?
@BrianC614 Nope! I'll let you know as soon as we figure it out though! haha
at the very bottom:
"Replaces" Header
Availability: Since 9.0.7

MS Teams Direct Routing will stop processing inbound SIP Requests which have "Replaces" headers. This change is automatically done by the SBC Edge software upgrade. No configuration changes are needed. For more information, refer to MC299922.

We're already on 11.0.0, so....
@BrianC614 hmmm, we are on SWe Lite 9.0.2, looks like we might need to try and upgrade and see if we are still having the issue. This may not be the issue though since you are already updated and facing the same issue. It is definitely a little too coincidental that they made this change and all of a sudden we are having the issue. We weren't having the issue yesterday though, it just started today for us.
My previous version was 9.0.6, so I unfortunately don't have 9.0.7 on my application partition. I am going to try downloading it now and putting it on my secondary SBC and forcing calls through it for testing, in case 9.0.7 works and 11.0.0 does not.
Check this link out @BrianC614 , Ribbon actually provides a date of April 5th in the table that Microsoft plans to stop processing calls with the Replaces header:
Chatting with Ribbon Support - the updates are in 9.0.7, but not 11.0.0. They say they will be in 11.0.1, but have not answered me on when 11.0.1 will be released, so I am attempting to "downgrade" from 11.0.0 to 9.0.7 on our secondary SBC.
@BrianC614 Well that's just lovely! Glad we are headed in the right direction, we are planning our upgrade in about an hour, I'll let you know how it goes.
It seems like the downgrade to 9.0.7 worked. Having to do some more thorough testing to be sure, and we're at least in a better place than we were before. I'll update once I've done more testing.

@BrianC614 We just completed the upgrade to 9.0.7 and it fixed our issue! Thanks for your help on this, hope your testing is going well and you are back in business!