Malformed SIP request received , is this the problem 'Date: Tue, 03 Nov 2026 12:16:06 EET'

[grhookgr]

11/03/2026 12:16:38.014 PM

Hi all, I manage an on-premises 3CX server running on Windows. Everything works fine, except when we receive a call from one specific number. In that case the Activity Log shows “Malformed SIP request received” and the call fails. System:Version 20.0 Update 9 (Build 995 Release - AI 1.4.48) After some searching, I found an older forum thread where the cause was a non-GMT time zone in the SIP Date header. In my INVITE the Date line is: Date: Tue, 03 Nov 2026 12:16:06 EET As far as I understand, the SIP spec only allows GMT in this header, and 3CX seems to reject anything else. Full log entry: Malformed SIP request received: BadSip Recv 200/INVITE from 10.124.45.84:5060 tid=3f7a0757e3481c7a Call-ID=VsDC-lHE0o6QlV2vXUowww..: SIP/2.0 200 OKVia: SIP/2.0/UDP 172.****:5060; received=172.1****;rport=5060;branch=z9hG4bK-524287-1---3f7a0757e3481c7a Record-Route: <sip:10.124.45.84;transport=udp;lr> Contact: <sip:[email protected];transport=udp>;+g.3gpp.icsi-ref="urn%3Aurn-7%3A3gpp-service.ims.icsi.mmtel"To: <sip:21032*****@10.124.45.84:5060>; tag=h7g4Esbg_p65540t1793700966m89844c101098s1_2364196977-477482903 From: "+3021048******" <sip:+3021048*****@10.124.45.84:5060;user=phone>; tag=b258cd0bCall-ID: VsDC-lHE0o6QlV2vXUowww..CSeq: 1 INVITESession-Expires: 1800;refresher=uas Allow: REGISTER, REFER, NOTIFY, SUBSCRIBE, UPDATE, INVITE, ACK, OPTIONS, CANCEL, BYEContent-Type: application/sdp Date: Tue, 03 Nov 2026 12:16:06 EET Server: Ericsson MTAS - CXP2010134 1.36.1-1 Supported: timer, replacesAllow-Events: telephone-event Session-ID: 34e113dfd30350dbbf9b5ac22238964f;remote=db46632d77ac5841b30cde2a67c3f45b Content-Length: 193v=0o=- 896850483236820 3672431812 IN IP4 10.124.45.84s=-c=IN IP4 10.124.47.133t=0 0m=audio 39418 RTP/AVP 8 101c=IN IP4 10.124.47.133a=rtpmap:101 telephone-event/8000a=ptime:20 My questions: Can anyone confirm that 3CX rejects a Date header with a non-GMT time zone such as EET? Is there any setting in 3CX to make it more tolerant of this, or is the only fix to have the sender (the carrier or gateway) send the Date in GMT or remove it? Has anyone dealt with this on a trunk from an Ericsson IMS core?

 

[KyriacosS_3CX]

Hello, you should really post this in a more relevant section. Also, have you raised this with your SIP Trunk provider?

 

[TheodorosG_3CX]

Yes this must not be posted in here, however this is defined as per RFC3261 in section 20.17 that only GMT is accepted therefore this will be rejected as expected from the PBX. This is default and cannot be changed or modified. You need to ask your provider or use one of 3CX Supported to avoid such issues.

 

[grhookgr]

Thank you for all your answers i will contact my sip provider (nova greece)