Malformed SIP request received

[[email protected]]

We are setting up an Azure hosted 3CX instance with an unsupported SIP provider for one of our larger clients. The SIP provider handles this client's internet and site connectivity and the client does not want to switch providers. We used the Azure 3CX template so all firewall rules appear to be correct and pass. The SIP trunk provided for testing is IP based. I set this up using a generic SIP trunk with the default settings. Outbound calls work correctly. Inbound calls timeout and the SIP provider tells me they are not receiving a rely to their INVITE request. The logs show a malformed SIP request received (hoping this entry is sanitized enough).

02/26/2021 3:01:59 PM - Malformed SIP request received:
BadSip Recv Req INVITE from xx.xx.xx.xx:5060 tid=+287cf5dcdc09b85f26b02ddb23e9bbe41+sip+1+1d539135 Call-ID=0gQAAC8WAAACBAAALxYAAEhMytVvQp0J9NrnX2tsiBAfGJQ4zq61tg+6cfYNJJbB@xx.xx.xx.xx:
INVITE sip:[email protected]:5060;transport=udp SIP/2.0
Via: SIP/2.0/UDP xx.xx.xx.xx:5060;branch=z9hG4bK+287cf5dcdc09b85f26b02ddb23e9bbe41+sip+1+1d539135
Max-Forwards: 25
Contact: <sip:[email protected]:5060>;isup-oli=00
To: <sip:[email protected]>
From: "WIRELESS CALLER" <sip:[email protected]:5060>;tag=xx.xx.xx.xx+1+6b5d64a8+a0f99da6;isup-oli=00
Call-ID: 0gQAAC8WAAACBAAALxYAAEhMytVvQp0J9NrnX2tsiBAfGJQ4zq61tg+6cfYNJJbB@xx.xx.xx.xx
CSeq: 993598857 INVITE
Expires: 180
Alert-Info: info=<Bellcore-dr3>
Content-Type: application/sdp
Supported: resource-priority, siprec, 100rel
Allow-Events: message-summary, refer, dialog, line-seize, presence, call-info, as-feature-event, calling-name, ua-profile
P-Asserted-Identity: "WIRELESS CALLER" <sip:[email protected]:5060>
Content-Length: 138

v=0
o=- xxxxxxxxxxxxxxxx xxxxxxxxxxxxxx IN IP4 xx.xx.xx.xx
s=-
c=IN IP4 xx.xx.xx.xx
t=0 0
m=audio 59926 RTP/AVP 0
a=ptime:20

I have tried using both the provider's IP/domain in the proxy field along with both fixed port 5060/auto discovery options. I have tried a few different inbound parameters, but I am not sure what to look for next.

I tested the PBX with an account/register based SIP trunk from another provider and inbound and outbound calls work perfectly. Any assistance from anyone familiar with similar SIP issues would be greatly appreciated.

 

[cobaltit]

So you didn't mention the provider which might help. But realistically you need to tell the client that to make this work you need to block out time with one of the provider's engineers and then collaborate to make this work. Or they need to bite the bullet and switch to a supported provider (I know one ). The primary benefit of sticking with the SIP trunk from the same company that provides the bandwidth is call quality guarantees but that went out the window the moment you said Azure.