Fax tone on inbound calls

[Jonners59]

I am getting a fax tone on in-bound calls instead of either going to Hunt Group, Digital Receptionist or Voice Mail.

In-bound calls come in on (2x) PSTN lines via a Grandstream GWX 4104 FXO/FXS (IP 192.168.1.95) and then hit the 3CX on Server IP 192.168.1.50. They both sit on a LAN with a router (192.168.1.1), Draytek 2820 at its centre. I have also set up the router as an extension too for traditional outbound faxes using the SIP account facility on the router and an extension on the 3CX – it is registered and works. I know this is not the cause for a number of reasons. The problem occurred before I set this up. It is on a different PSTN line and it is NOT in the in-bound calling group.

An inbound call should work in the following way – 2 options I have tried:
Call comes in on main line and is directed to Ring Group 801 where is rings all associated extensions. After 30 seconds it should go to Digital Receptionist 806, where there are options.... The fax tone starts at the point where the call is meant to have been routed to the DR 806.

Option 2, I changed the above slightly such that extension 110 has forward all calls to RG 801 (110 is in RG 801 as one of the available extensions). I also set the in-bound calls for this PSTN line from the GW ch to route to Extn 110. This made absolutely no difference. The calls ring all extensions as planned and as above, but when the 30 seconds are up, instead of going to DR 806, I get a fax tone.

The 3CX log shows the following for a typical call using option 2 above:

09:14:40.966 [MS105000] C:46.1: No RTP packets were received:remoteAddr=192.168.1.95:5008,extAddr=0.0.0.0:0,localAddr=192.168.1.50:7204
09:14:40.907 [CM503003]: Call(46): Call to sip:[email protected] has failed; Cause: 487 Request Terminated; from IP:192.168.1.75:61672
09:14:39.847 [CM503007]: Call(46): Device joined: sip:[email protected]:40600;rinstance=14e755b45b816b94
09:14:39.823 Session 38264 of leg C:46.1 is confirmed
09:14:39.793 [CM503007]: Call(46): Device joined: sip:[email protected]:5064;transport=udp
09:14:39.779 [MS210003] C:46.1:Answer provided. Connection(transcoding mode[unsecure]):192.168.1.50:7204(7205)
09:14:39.753 [MS210001] C:46.4:Answer received. RTP connection[unsecure]: 127.0.0.1:40628(40629)
09:14:39.656 Remote SDP is set for legC:46.4
09:14:39.650 [CM505001]: Ext.806: Device info: Device Identified: [Man: 3CX Ltd.;Mod: 3CX IVR;Rev: General] Capabilities:[reinvite, replaces, able-no-sdp, recvonly] UserAgent: [3CX IVR] PBX contact: [sip:[email protected]:5060]
09:14:39.650 [CM503002]: Call(46): Alerting sip:[email protected]:40600;rinstance=14e755b45b816b94
09:14:39.414 [CM503003]: Call(46): Call to sip:[email protected] has failed; Cause: 487 Request Cancelled; from IP:192.168.1.90:5060
09:14:39.412 [CM503025]: Call(46): Calling Ext:Ext.806@[Dev:sip:[email protected]:40600;rinstance=14e755b45b816b94]
09:14:39.389 [MS210002] C:46.4:Offer provided. Connection(transcoding mode): 127.0.0.1:7210(7211)
09:14:39.226 [CM503005]: Call(46): Forwarding: Ext:Ext.806@[Dev:sip:[email protected]:40600;rinstance=14e755b45b816b94]
09:14:10.066 [CM505001]: Ext.110: Device info: Device Not Identified: User Agent not matched; Capabilities:[reinvite, replaces, able-no-sdp, recvonly] UserAgent: [A580 IP022140000000] PBX contact: [sip:[email protected]:5060]
09:14:10.066 [CM503002]: Call(46): Alerting sip:[email protected]:5060
09:14:09.580 [CM505001]: Ext.105: Device info: Device Identified: [Man: Counterpath;Mod: X-Lite;Rev: General] Capabilities:[reinvite, no-replaces, unable-no-sdp, recvonly] UserAgent: [X-Lite release 1103k stamp 53621] PBX contact: [sip:[email protected]:5060]
09:14:09.580 [CM503002]: Call(46): Alerting sip:[email protected]:61672;rinstance=50e6db28740b206c
09:14:09.168 [CM503025]: Call(46): Calling RingAll801:110Ext.110105Ext.105111Ext.111@[Dev:sip:[email protected]:61672;rinstance=50e6db28740b206c]
09:14:09.140 [MS210002] C:46.3:Offer provided. Connection(transcoding mode): 192.168.1.50:7208(7209)
09:14:09.025 [CM503025]: Call(46): Calling RingAll801:110Ext.110105Ext.105111Ext.111@[Dev:sip:[email protected]:5060]
09:14:09.000 [MS210002] C:46.2:Offer provided. Connection(transcoding mode): 192.168.1.50:7206(7207)
09:14:08.843 [MS210000] C:46.1:Offer received. RTP connection: 192.168.1.95:5008(5009)
09:14:08.841 [CM503004]: Call(46): Route 1: RingAll801:110Ext.110105Ext.105111Ext.111@[Dev:sip:[email protected]:5060,Dev:sip:[email protected]:61672;rinstance=50e6db28740b206c]
09:14:08.835 [CM503010]: Making route(s) to <sip:[email protected]:5060>
09:14:08.797 Remote SDP is set for legC:46.1
09:14:08.796 [CM505002]: Gateway:[PSTN] Device info: Device Not Identified: User Agent not matched; Capabilities:[reinvite, replaces, able-no-sdp, recvonly] UserAgent: [Grandstream GXW4104 (HW 1.1, Ch:1) 1.3.1.6] PBX contact: [sip:[email protected]:5060]
09:14:08.732 [CM503001]: Call(46): Incoming call from unknown@(Ln.10003@PSTN) to <sip:[email protected]:5060>
09:14:08.679 [CM503012]: Inbound out-of-office hours rule (unnamed) for 10003 forwards to DN:110
09:14:08.678 Looking for inbound target: called=444; caller=unknown
09:14:08.659 [CM500002]: Info on incoming INVITE:
INVITE sip:[email protected] SIP/2.0
Via: SIP/2.0/UDP 192.168.1.95:5064;branch=z9hG4bKe752a3b05453b105
Max-Forwards: 70
Contact: <sip:[email protected]:5064;transport=udp>
To: <sip:[email protected]>
From: <sip:[email protected]>;tag=9295052753e255e6
Call-ID: [email protected]
CSeq: 10962 INVITE
Allow: INVITE, ACK, CANCEL, BYE, NOTIFY, REFER, OPTIONS, INFO, SUBSCRIBE, UPDATE, PRACK
Proxy-Authorization: Digest username="10003",realm="3CXPhoneSystem",algorithm=MD5,uri="sip:[email protected]",nonce="414d535c0147b66084:91eae574e4e548bcf72d56f727eb07a7",response="2b53f1e6925466d532ac38f89e37f782"
Supported: replaces, timer, path
User-Agent: Grandstream GXW4104 (HW 1.1, Ch:1) 1.3.1.6
Content-Length: 0

 

[leejor]

If it is an actual fax tone then it come from one of two places, an external fax machine or the fax server within 3CX. If you aren't planning on using the fax server , you can turn it off. Go to Services Status and stop the FAX server.

 

[Jonners59]

I had already tried removing the fax devices and it made no difference, unless either the Grandstream or the Draytek are answering in some way. Otherwise it has to be something to do with the 3CX. It happens as it transfers over to the IVR extension 806.

I have tried turning off the Fax Server capability. This made no difference. It still gave the fax tone as it transfered. In some ways fortunately, because if it had been the answer then I would have had to have left it in "stopped" mode, and when ever the Server did a re-start after a software upgrade it would have had to have been truned off again, which would have been a problem if it were a Windows auto update and I was not about.

That said, as it was not the answer. Any other ideas, please????????

 

[SY]

I had already tried removing the fax devices and it made no difference, unless either the Grandstream or the Draytek are answering in some way. Otherwise it has to be something to do with the 3CX. It happens as it transfers over to the IVR extension 806.

I have tried turning off the Fax Server capability. This made no difference. It still gave the fax tone as it transfered. In some ways fortunately, because if it had been the answer then I would have had to have left it in "stopped" mode, and when ever the Server did a re-start after a software upgrade it would have had to have been truned off again, which would have been a problem if it were a Windows auto update and I was not about.

That said, as it was not the answer. Any other ideas, please????????

Two questions:
1. What is the device which delivers call to PBX?
2. What is the reaction of phone system when you call 806 from "local" extension (SIP phone)?

Thanks

 

[Jonners59]

Re above Q1 The device is the Grandstream GW4104
Q2 It works....

 

[leejor]

Are you sure it is a fax tone... modulated modem sound, then a pause, then back again? Or is it just a solid tone, single frequency tone?

 

[Jonners59]

A good point.

It is a single tone for a few seconds, then up a tone for about a second then silence.... Does this help?

 

[leejor]

You don't have any PC modems, security systems (on the same PSTN line) or any other devices that could be generating modem tones at all?

 

[Jonners59]

If you see above in my initial query, what I have is as follows:
1. Grandstream GWX4104, which is my main FXO/FXS for the two telephone lines to 3CX
2. Draytek 2820 Router to manage the FW, LAN and DSL, but it also has an FXO/FXS which I have set up to be a FAX extension off the 3CX and I have plugged the two fax devices in to this (fax machine and PC card). I have tried this with the devices plugged in and taken out and the UN & PW removed from the Draytek to confirm it is they that is causing the problem or not. It still occurred with or without them.
3. I also have a Siemens A580 IP DECT handset(s) attached via two extensions, one for work (100) and one for Home (110).

The Grandstream has a T38 capability enabled and that is set for Passthrough and ecm. Could this be the Grandstream?

 

[SY]

...
The Grandstream has a T38 capability enabled and that is set for Passthrough and ecm. Could this be the Grandstream?

To check it, you may disable t38 on Grandstream

 

[Jonners59]

Does not disable.... This is driving me mad!

 

[leejor]

I guess that you don't have access to another Gateway to use for testing? Perhaps apply a free VoIP trunk from SipPhone (do a search of the forum as to problems getting a SipPhone trunk to register and the changes you have to do) to do some incoming call tests to incriminate or eliminate the gateway as the problem.

 

[Jonners59]

I have tried with the router, the fax machine, fax PCI Card and the DECT (Siemens) phone all removed, so we only have the phone line coming in to the Grandstream and in to the 3CX Server. It still did it.

Add to stopping the fax server on the 3CX it only leave two items that can cause this:
Grandstream
3CX

 

[leejor]

And the only way to eliminate the Grandstream as the culprit is to try another gateway.

 

[Jonners59]

Re: Fax tone on inbound calls - SOLUTION

SOLUTION:
The problem is the Grandstream assumes a call is NOT established if it rings for greater than 30 seconds. In my case that is just at the point the call is redirected to the IVR!

Solution(s);
Shorten the time before the call is forward, hence giving the impression the call has been answered or

Grandstream's option - all in quotes, italics and blue:

"This device may appear to hang up calls which are not answered within 30 seconds. This behavior is due to the device considering that the call is NOT ESTABLISHED until some extension answers.

To enable complex call forwarding which may require over 30 seconds before call pickup, a workaround will be necessary.
1. Create a Digital Receptionist, attaching a short audio prompt (we suggest you use a silent 1-second WAV file).
2. Set Timeout to 1 second.
3. Set your intended forwarding using the “Action after timeout” and “Extension Number” fields.
4. Leave all key actions to “0 No Action”
5. Go to the bottom of the page and click OK".

 

[SY]

Re: Fax tone on inbound calls - SOLUTION

SOLUTION:
The problem is the Grandstream assumes a call is NOT established if it rings for greater than 30 seconds. In my case that is just at the point the call is redirected to the IVR!

Solution(s);
Shorten the time before the call is forward, hence giving the impression the call has been answered or

Grandstream's option - all in quotes, italics and blue:

"This device may appear to hang up calls which are not answered within 30 seconds. This behavior is due to the device considering that the call is NOT ESTABLISHED until some extension answers.

To enable complex call forwarding which may require over 30 seconds before call pickup, a workaround will be necessary.
1. Create a Digital Receptionist, attaching a short audio prompt (we suggest you use a silent 1-second WAV file).
2. Set Timeout to 1 second.
3. Set your intended forwarding using the “Action after timeout” and “Extension Number” fields.
4. Leave all key actions to “0 No Action”
5. Go to the bottom of the page and click OK".

How does this description explain the "FAX tone and then silence..." situation?
Thanks

 

[Jonners59]

That is a valid point that I am discussing with Grandstream. I can only state that Grandstream said that the device does not like calls taking over 30 seconds to be unanswered. It then rejects the call. I can also only add that the device has a T38/fax capability, but they then go on to say there is nothing wrong with the 4104 the problem is with 3CX. Interesting thought given the circumstances.

I have suggested that they should have an option to turn the fax facility off, and that they offer options to change the call reject delay in event of calls not being answered to suit the users needs and wishes.

Which of the two "devices" is providing the tone and what the cause of the 'error' is I can not answer. I don't have the knowledge or facilities to deal with it.

I can also only add that the fix worked and is a work around or a senario for users to be aware of, for now at least. As you are a 3CX developer you may have a better idea, you may also be able to answer my other problem regarding stripping SIP information (http://www.3cx.com/forums/remove-sip-info-on-in-bound-caller-id-12718.html)