Faxing via a Handytone HT-286

[Worm78]

I had fax machine working for a while on an old SPA2001. I was troubleshooting another issue and now it does not work. I then upgraded to a Handytone 286 as the SPA was a bit iffy. ATA connects and works like a phone with no issues. I have the ATA and the pbx ext set to use G711. I have it set on pass through mode. Here is the log during the issue. It seems to try and handshake then goes silent.

 

Any ideas?

 

[7] 2009/04/10 10:50:29: Set packet length to 20

[6] 2009/04/10 10:50:29: Sending RTP for 6034554a414b8a2b@192.168.10.203#20f0a6c98b to 192.168.10.203:5004

[7] 2009/04/10 10:50:29: Set packet length to 20

[7] 2009/04/10 10:50:29: Receiving DTMF on codec 101

[7] 2009/04/10 10:50:29: Set packet length to 20

[6] 2009/04/10 10:50:29: Sending RTP for 1b1dee70@pbx#1336573554 to 63.211.239.14:30626

[7] 2009/04/10 10:50:30: Receiving DTMF on codec 101

[7] 2009/04/10 10:50:30: 1b1dee70@pbx#1336573554: RTP pass-through mode

[7] 2009/04/10 10:50:30: 6034554a414b8a2b@192.168.10.203#20f0a6c98b: RTP pass-through mode

[7] 2009/04/10 10:50:30: Call 1b1dee70@pbx#1336573554: Clear last request

[7] 2009/04/10 10:50:32: Call 1b1dee70@pbx#1336573554: Clear last INVITE

[7] 2009/04/10 10:50:32: Set packet length to 20

[7] 2009/04/10 10:50:32: Determine pass-through mode after receiving response

[7] 2009/04/10 10:51:29: Set packet length to 20

[7] 2009/04/10 10:51:39: 1b1dee70@pbx#1336573554: Media-aware pass-through mode

[7] 2009/04/10 10:51:39: Other Ports: 1

[7] 2009/04/10 10:51:39: Call Port: 1b1dee70@pbx#1336573554

[7] 2009/04/10 10:51:39: Call 1b1dee70@pbx#1336573554: Clear last request

[5] 2009/04/10 10:51:39: BYE Response: Terminate 1b1dee70@pbx

 

The fax is set to 14,400 , ECM is turned off.

 

Error kicked back on fax report is comm error.

 

Using the standard phone seems very clear and a good bi-way audio signal.

[Vodia PBX]

We have such a HT in an office, and it works with T.38 (though we have to reboot it from time to time in order to keep receiving FAX).

 

The CS410 PSTN gateway does not support T.38; therefore you must use G.711 for the FAX. If the FAX is in the office (same LAN) that should be okay. I remember there are a couple of settings for the HT regarding FAX. Maybe double check and make sure it does not use T.38.

[Worm78]

We have such a HT in an office, and it works with T.38 (though we have to reboot it from time to time in order to keep receiving FAX).

 

The CS410 PSTN gateway does not support T.38; therefore you must use G.711 for the FAX. If the FAX is in the office (same LAN) that should be okay. I remember there are a couple of settings for the HT regarding FAX. Maybe double check and make sure it does not use T.38.

 

 

I'm currently using the Fax Pass Through mode, My SIP trunk provider (Teliax) does not support T38.

 

I was on an older version of the CS410 and using the spa2001 and I had no issues. Unfortunately over the last six months I was battling a 4 second intermittent silence issue. That was recently resolved. It was a cable modem with ARP storm detection enables causing the issue. I still need to update my other 400 page post still. In that time, I upgraded to the latest software on the cs410, we changed the fax machine as the other one died, and I'm sure I have changed some settings on the PBX. All was well on the PBX side until we tried to fax. I worked with the SPA2001 for a week and reads horrible things. I upgraded to the ht286 and still no luck. Audio is crystal clear if I use the handset or a regular phoneo n the fax line. It is forced on g711u. We don't do much faxing and are ok with the occasional issue but I have tried 30 pages and not one has went through. Always a comm error. I hear the dee dee dee da shhhh and then i see the call online from the pbx for 60 more seconds or so. My guess it is some echo or silence supression issue. You mentioned this on another post but not sufre how to change on the cs410

 

"One common problem with the Gradstream devices is that they advertize UPDATE, but when they receive a UPDATE message with a SDP offer, they don't answer this.

 

What you can do is to turn off the support for UPDATE. The setting is called "support_update" and is in the http://wiki.pbxnsip.com/index.php/Global_Configuration_File. I would try to set it to "false". ".

 

 

 

Here is what Teliax says. I'm awaiting a reply from the support line. Is there anywhere in the CS410 to limit audio correction or clipping? They have an inbound fax service we will use for all inbound items.

 

5. Can I use my fax machine?

Yes. In most cases you can use a fax machine but this service is not 100% guaranteed. VoIP uses compression technology to preserve bandwidth and send a high quality voice signal accross the internet. Part of compressing a voice signal involves removing the higher and lower portions of the voice frequency being sent over the internet. These frequencies are inaudible to the human ear but are very important to machines like faxes. We have some special instructions for faxing over the TelIAX network. Please email us at support@teliax.com for more information.

 

Thanks,

Brian

[Vodia PBX]

I'm currently using the Fax Pass Through mode, My SIP trunk provider (Teliax) does not support T38.

 

T.38 has been invented for a reason. The reason is that SIP trunking very easily looses packets. If you loose one packet when receiving a FAX, the rest of the page might become completely black (or white, if you are lucky).

 

I was on an older version of the CS410 and using the spa2001 and I had no issues. Unfortunately over the last six months I was battling a 4 second intermittent silence issue. That was recently resolved. It was a cable modem with ARP storm detection enables causing the issue. I still need to update my other 400 page post still. In that time, I upgraded to the latest software on the cs410, we changed the fax machine as the other one died, and I'm sure I have changed some settings on the PBX. All was well on the PBX side until we tried to fax. I worked with the SPA2001 for a week and reads horrible things. I upgraded to the ht286 and still no luck. Audio is crystal clear if I use the handset or a regular phoneo n the fax line. It is forced on g711u. We don't do much faxing and are ok with the occasional issue but I have tried 30 pages and not one has went through. Always a comm error. I hear the dee dee dee da shhhh and then i see the call online from the pbx for 60 more seconds or so. My guess it is some echo or silence supression issue. You mentioned this on another post but not sufre how to change on the cs410

 

The CS410 does not change anything regarding echo compensation or silence suppression. Once the two calls are connected the PBX happily passes the audio packets from one side to another and that's it (unless you are performing transcoding). If the provider performs echo compensation on a FAX this might be an issue.

 

"One common problem with the Gradstream devices is that they advertize UPDATE, but when they receive a UPDATE message with a SDP offer, they don't answer this.

 

Well, that is a major bug that they should really fix.

 

What you can do is to turn off the support for UPDATE. The setting is called "support_update" and is in the http://wiki.pbxnsip.com/index.php/Global_Configuration_File. I would try to set it to "false". ".

 

Right, unfortunately in the SIP world Grandstream is not the only vendor with problems implementing UPDATE correctly... Check the pbx.xml file to see what the current value is.

 

Here is what Teliax says. I'm awaiting a reply from the support line. Is there anywhere in the CS410 to limit audio correction or clipping? They have an inbound fax service we will use for all inbound items.

 

The only thing that I can think of is transcoding. But if you are using G.711 on both sides, the signal should not be changed at all. The PBX also does not perform VAD, and does not advertize this.

 

5. Can I use my fax machine?

 

Yes. In most cases you can use a fax machine but this service is not 100% guaranteed. VoIP uses compression technology to preserve bandwidth and send a high quality voice signal accross the internet. Part of compressing a voice signal involves removing the higher and lower portions of the voice frequency being sent over the internet. These frequencies are inaudible to the human ear but are very important to machines like faxes. We have some special instructions for faxing over the TelIAX network. Please email us at support@teliax.com for more information.

 

Well, FAX is a problem in the VoIP world, this is not only a Teliax problem. T.38 does solve the problem of packet loss and it makes FAX possible over the regular Internet.

 

T.38 sounds like a solution that they should support, but the interoperability in T.38 is lously. And there is not even a way to encrypt T.38 packets like RTP and SRTP. T.38 does not even use RTP.