SIP Trunk gets 503 Service Unavailable

[interopPbxs]

I am routing a call using SIP into the Mitel. I am getting a 503 Service Unavailable response. In this case the RequestURI and To is a user registered on a 5212 phone. The From is an unknown user and is not data filled on Mitel.

I verified that I am hitting the Sip Peer because I can toggle on/off the "Authentication Option for Incoming Calls". When set to "Challenge-based" the call is correctly challenged.

Any ideas as to what is causing the 503 Service Unavailable response.

[ralph]

Try looking at the COS to verify that "Public Network" connections are allowed.  That and interconnect restriction.  Also check the trunk service assignment form to be sure the number of digits to absorb is set to '0' not nul.
I'd bet the issue is in the COS.

Ralph

[interopPbxs]

Thanks....

The problem was the number of digits to absorb. Changed it from a blank field to 0 and calls started to work.

[ralph]

Beauty.  Thanks for letting us know what fixed it.

Ralph

[EllisD]

I have to post a thank-you in here also.  Spent 2 days trying to figure out this exact same problem.

Changed the null to a 0 and bingo!!

Thanks.

[GZgidnick]

Ralph, I feel obliged to thank you 7 years after this original post.
Dial In Trunks Incoming Digit Modification - Absorb = 0
Who could possibly think of! What a catch!

[ralph]

Thank you. GZgidnick.

That's one of the things I like about this forum is that there is a lot of great history building up that always seems to be relevant and useful.
There are so many excellent technical people here willing to share that it certainly makes things a lot easier.
So I put my own great big "Thank You" to everyone who participates.

Ralph

[x-man]

Is that not simply that the absorb field or answer point must be filled in; one or the other but not both as they are mutually exclusive? Just to clarify why one or the other must be filled with a value but not both for incoming service to work. Of course if the answer point is invalid then that also would stop incoming calls.

[ralph]

If you're expecting digits then you need to apply the absorb 0.
It never made sense to me that you should have to put anything other than a non-0 value it there.   Why wouldn't the assumed value be 0?

If you're not expecting digits, such as with loop start trunks or ARD/MRDs then you need to put a valid ring to destination.
You'd actually have to work pretty hard to put an invalid destination number in there because it checks to be sure it's valid before you can save it.

Ralph

[x-man]

Actually I've just remembered that you can't fill one in if the other has an entry as it pops up a error (which is what brought it to mind when you mentioned checking)

I think the thinking may have been that if you are going to be expecting numbers then there cannot be an assumed number to absorb and that 0 is just as valid as 6....?

[alex053]

i know this is old as dirt but it came up on my google search so it may help someone else down the road.

we were adding another sip peer profile and everything looked good but we got the 503 error.

we found that the other two sip peer profiles had all the sip trunk licenses reserved. 

so two sip peer profiles, 60 total licenses and each had 30 provisioned for it.  i freed some up and inbound started workimg