Can't receive inbound faxes. Failed to initialize UDPTL, No acceptable offer found

Having an issue receiving inbound faxes. Configured a DID, inbound route with faxdetect yes, SIP, sending the destination to a fax enabled user with a valid email. All other email related functions work.

When receiving a fax I get the following CLI output

== Using SIP RTP TOS bits 184
== Using SIP RTP CoS mark 5
> 0x7f18de567c70 – Strict RTP learning after remote address set to: x.xx.xx.xxx:17990
– Executing [[email protected]_1:1] Set(“SIP/BBD_1-0000016a”, “GROUP()=OUT_1”) in new stack
– Executing [[email protected]_1:2] Goto(“SIP/BBD_1-0000016a”, “from-trunk,2677932925,1”) in new stack
– Goto (from-trunk,2677932925,1)
– Executing [[email protected]:1] Set(“SIP/BBD_1-0000016a”, “__DIRECTION=INBOUND”) in new stack
– Executing [[email protected]:2] Gosub(“SIP/BBD_1-0000016a”, “sub-record-check,s,1(in,2677932925,no)”) in new stack
– Executing [[email protected]:1] GotoIf(“SIP/BBD_1-0000016a”, “0?initialized”) in new stack
– Executing [[email protected]:2] Set(“SIP/BBD_1-0000016a”, “__REC_STATUS=INITIALIZED”) in new stack
– Executing [[email protected]:3] Set(“SIP/BBD_1-0000016a”, “NOW=1515224033”) in new stack
– Executing [[email protected]:4] Set(“SIP/BBD_1-0000016a”, “__DAY=06”) in new stack
– Executing [[email protected]:5] Set(“SIP/BBD_1-0000016a”, “__MONTH=01”) in new stack
– Executing [[email protected]:6] Set(“SIP/BBD_1-0000016a”, “__YEAR=2018”) in new stack
– Executing [[email protected]:7] Set(“SIP/BBD_1-0000016a”, “__TIMESTR=20180106-073353”) in new stack
– Executing [[email protected]:8] Set(“SIP/BBD_1-0000016a”, “__FROMEXTEN=unknown”) in new stack
– Executing [[email protected]:9] Set(“SIP/BBD_1-0000016a”, “__MON_FMT=wav”) in new stack
– Executing [[email protected]:10] NoOp(“SIP/BBD_1-0000016a”, “Recordings initialized”) in new stack
– Executing [[email protected]:11] ExecIf(“SIP/BBD_1-0000016a”, “0?Set(ARG3=dontcare)”) in new stack
– Executing [[email protected]:12] Set(“SIP/BBD_1-0000016a”, “REC_POLICY_MODE_SAVE=”) in new stack
– Executing [[email protected]:13] ExecIf(“SIP/BBD_1-0000016a”, “0?Set(REC_STATUS=NO)”) in new stack
– Executing [[email protected]:14] GotoIf(“SIP/BBD_1-0000016a”, “2?checkaction”) in new stack
– Goto (sub-record-check,s,17)
– Executing [[email protected]:17] GotoIf(“SIP/BBD_1-0000016a”, “1?sub-record-check,in,1”) in new stack
– Goto (sub-record-check,in,1)
– Executing [[email protected]:1] NoOp(“SIP/BBD_1-0000016a”, “Inbound Recording Check to 2677932925”) in new stack
– Executing [[email protected]:2] Set(“SIP/BBD_1-0000016a”, “FROMEXTEN=unknown”) in new stack
– Executing [[email protected]:3] ExecIf(“SIP/BBD_1-0000016a”, “10?Set(FROMEXTEN=6193694525)”) in new stack
– Executing [[email protected]:4] Gosub(“SIP/BBD_1-0000016a”, “recordcheck,1(no,in,2677932925)”) in new stack
– Executing [[email protected]:1] NoOp(“SIP/BBD_1-0000016a”, “Starting recording check against no”) in new stack
– Executing [[email protected]:2] Goto(“SIP/BBD_1-0000016a”, “no”) in new stack
– Goto (sub-record-check,recordcheck,12)
– Executing [[email protected]:12] Set(“SIP/BBD_1-0000016a”, “__REC_POLICY_MODE=NO”) in new stack
– Executing [[email protected]:13] Return(“SIP/BBD_1-0000016a”, “”) in new stack
– Executing [[email protected]:5] Return(“SIP/BBD_1-0000016a”, “”) in new stack
– Executing [[email protected]:3] Gosub(“SIP/BBD_1-0000016a”, “app-blacklist-check,s,1()”) in new stack
– Executing [[email protected]:1] GotoIf(“SIP/BBD_1-0000016a”, “0?blacklisted”) in new stack
– Executing [[email protected]:2] Set(“SIP/BBD_1-0000016a”, “CALLED_BLACKLIST=1”) in new stack
– Executing [[email protected]:3] Return(“SIP/BBD_1-0000016a”, “”) in new stack
– Executing [[email protected]:4] Set(“SIP/BBD_1-0000016a”, “__FROM_DID=2677932925”) in new stack
– Executing [[email protected]:5] Set(“SIP/BBD_1-0000016a”, “CDR(did)=2677932925”) in new stack
– Executing [[email protected]:6] ExecIf(“SIP/BBD_1-0000016a”, “1 ?Set(CALLERID(name)=6193694525)”) in new stack
– Executing [[email protected]:7] Set(“SIP/BBD_1-0000016a”, “__MOHCLASS=”) in new stack
– Executing [[email protected]:8] Ringing(“SIP/BBD_1-0000016a”, “”) in new stack
– Executing [[email protected]:9] Set(“SIP/BBD_1-0000016a”, “__RINGINGSENT=TRUE”) in new stack
– Executing [[email protected]:10] Set(“SIP/BBD_1-0000016a”, “__REVERSAL_REJECT=FALSE”) in new stack
– Executing [[email protected]:11] GotoIf(“SIP/BBD_1-0000016a”, “1?post-reverse-charge”) in new stack
– Goto (from-trunk,2677932925,13)
– Executing [[email protected]:13] NoOp(“SIP/BBD_1-0000016a”, “”) in new stack
– Executing [[email protected]:14] Wait(“SIP/BBD_1-0000016a”, “12”) in new stack
– Executing [[email protected]:15] Set(“SIP/BBD_1-0000016a”, “__CALLINGNAMEPRES_SV=allowed_not_screened”) in new stack
– Executing [[email protected]:16] Set(“SIP/BBD_1-0000016a”, “__CALLINGNUMPRES_SV=allowed_not_screened”) in new stack
– Executing [[email protected]:17] Set(“SIP/BBD_1-0000016a”, “CALLERID(name-pres)=allowed_not_screened”) in new stack
– Executing [[email protected]:18] Set(“SIP/BBD_1-0000016a”, “CALLERID(num-pres)=allowed_not_screened”) in new stack
– Executing [[email protected]:19] Set(“SIP/BBD_1-0000016a”, “__RVOL=10”) in new stack
– Executing [[email protected]:20] NoOp(“SIP/BBD_1-0000016a”, “CallerID Entry Point”) in new stack
– Executing [[email protected]:21] Set(“SIP/BBD_1-0000016a”, “FAX_DEST=ext-fax^105^1”) in new stack
– Executing [[email protected]:22] Set(“SIP/BBD_1-0000016a”, “FAXOPT(faxdetect)=yes”) in new stack
– Executing [[email protected]:23] Answer(“SIP/BBD_1-0000016a”, “”) in new stack
> 0x7f18de567c70 – Strict RTP switching to RTP target address x.xx.xx.xx:17990 as source
– Executing [[email protected]:24] Wait(“SIP/BBD_1-0000016a”, “4”) in new stack
> 0x7f18de567c70 – Strict RTP learning complete - Locking on source address 8.38.41.138:17990
– Executing [[email protected]:25] Goto(“SIP/BBD_1-0000016a”, “ext-fax,105,1”) in new stack
– Goto (ext-fax,105,1)
– Executing [[email protected]:1] Set(“SIP/BBD_1-0000016a”, “FAX_FOR=291 (105)”) in new stack
– Executing [[email protected]:2] NoOp(“SIP/BBD_1-0000016a”, “Receiving Fax for: 291 (105), From: “6193694525” <6193694525>”) in new stack
– Executing [[email protected]:3] Set(“SIP/BBD_1-0000016a”, “FAX_RX_USER=105”) in new stack
– Executing [[email protected]:4] Set(“SIP/BBD_1-0000016a”, “FAX_RX_EMAIL_LEN=27”) in new stack
– Executing [[email protected]:5] Goto(“SIP/BBD_1-0000016a”, “s,receivefax”) in new stack
– Goto (ext-fax,s,3)
– Executing [[email protected]:3] StopPlayTones(“SIP/BBD_1-0000016a”, “”) in new stack
– Executing [[email protected]:4] ReceiveFAX(“SIP/BBD_1-0000016a”, “/var/spool/asterisk/fax/1515224033.487.tif,f”) in new stack
– Channel ‘SIP/BBD_1-0000016a’ receiving FAX ‘/var/spool/asterisk/fax/1515224033.487.tif’
[2018-01-06 07:34:14] WARNING[9847][C-00000154]: chan_sip.c:10649 process_sdp: Failed to initialize UDPTL, declining image stream
[2018-01-06 07:34:14] WARNING[9847][C-00000154]: chan_sip.c:10828 process_sdp: Failing due to no acceptable offer found
== Spawn extension (ext-fax, s, 4) exited non-zero on ‘SIP/BBD_1-0000016a’
– Executing [[email protected]:1] GotoIf(“SIP/BBD_1-0000016a”, “1?failed”) in new stack
– Goto (ext-fax,h,104)
– Executing [[email protected]:104] NoOp(“SIP/BBD_1-0000016a”, “FAX FAILED for: 291 (105) , From: “6193694525” <6193694525>”) in new stack
– Executing [[email protected]:105] Macro(“SIP/BBD_1-0000016a”, “hangupcall,”) in new stack
– Executing [[email protected]:1] GotoIf(“SIP/BBD_1-0000016a”, “1?theend”) in new stack
– Goto (macro-hangupcall,s,3)
– Executing [[email protected]:3] ExecIf(“SIP/BBD_1-0000016a”, “0?Set(CDR(recordingfile)=)”) in new stack
– Executing [[email protected]:4] NoOp(“SIP/BBD_1-0000016a”, " monior file= ") in new stack
– Executing [[email protected]:5] AGI(“SIP/BBD_1-0000016a”, “attendedtransfer-rec-restart.php,”) in new stack
– Launched AGI Script /var/lib/asterisk/agi-bin/attendedtransfer-rec-restart.php
– <SIP/BBD_1-0000016a>AGI Script attendedtransfer-rec-restart.php completed, returning 0
– Executing [[email protected]:6] Hangup(“SIP/BBD_1-0000016a”, “”) in new stack
== Spawn extension (macro-hangupcall, s, 6) exited non-zero on ‘SIP/BBD_1-0000016a’ in macro ‘hangupcall’
== Spawn extension (ext-fax, h, 105) exited non-zero on ‘SIP/BBD_1-0000016a’

Kind of at my wits end here. Bought the damn fax pro module and cant get the inbound working. Please help…

hi there

fax pro has nothing to do with this process - fax reception is part of the freepbx core ; fax pro adds things like outbound fax from UCP, coversheets, …

the error boils down to these two lines:

[2018-01-06 07:34:14] WARNING[9847][C-00000154]: chan_sip.c:10649 process_sdp: Failed to initialize UDPTL, declining image stream
[2018-01-06 07:34:14] WARNING[9847][C-00000154]: chan_sip.c:10828 process_sdp: Failing due to no acceptable offer found

without knowing more related to versions involved or whats configured in asterisk sip settings / fax setttings my best guess is t38 negotiation failure … pull a pcap and check it out

if you get stuck with the anlaysis you can open a paid support ticket with us or get assistance from flowroute

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