Vitelity fax receiving. Hang up after initial handshake

[amygrant]

Picked up some Vitelity DIDs using the NV link yesterday. One of them is to be a dedicated fax line.

I am posting this here (instead of vitelity support) in case someone else runs into this problem in the future or someone here has already solved it.

Voice lines work fine but the fax line has an odd issue. I am not familiar with the technical terms for faxing, so I will use the term "handshake" to represent the sequence of tones a fax typically makes when answering. You know, you call a fax and hear a bunch of high pitched noises for a few seconds.. then it pauses then it tries the handshake again.

Ok, so here is the issue. If I call my vitelity fax line, I hear the initial handshake but nothing afterwards and the call is dropped. I don't hear a second try of initializing the fax.

So my vitelity trunk points to IAX extension 123 which has been set up for faxes. (following tshif 4 part tutorial here on the forums for hylafax/avantfax)

If I take a GoogleVoice trunk and point it to the same extension 123 and then call the GV#, I will hear the initial fax handshake and I will hear subsequent handshakes attempting to establish a fax communication.

So my GV trunk works but the vitelity trunk does not. I used the vitelity trunk settings that come with the PIAF install and simply added my account credentials.

Tailing the log on both calls leads me to believe it is an issue on the vitelity side because it seems like vitelity is the one terminating the call. Why or how they would be the cause of this is beyond me.

The only other issue I could think of is a trunk misconfiguration on my part but since I used the settings out of the box from PIAF, I would think they are kosher.

(BTW - I am aware that Vitelity offers vfax services but I wanted to keep everything under the same roof on my PIAF server and the vitelity vfax services have no DIDs available in Hawaii which is where I need. They do have HI DIDs for voice however.)

From sip_additional.conf:

[Vitelity-Fax]
disallow=all
username=MYUSERNAME
type=friend
t38pt_udptl=no   
t38pt_tcp=no
t38pt_rtp=no  
secret=MUSUPERSECRETPASSWORD
insecure=port,invite
host=inbound27.vitelity.net
context=from-trunk
canreinvite=no
allow=ulaw 
nat=yes

                                                               +------------------------System Information---------------------------+
                                                               |  Asterisk   = ONLINE  | Dahdi     = ONLINE  | MySQL     = ONLINE    |
                                                               |  SSH        = ONLINE  | Apache    = ONLINE  | Iptables  = ONLINE    |
                                                               |  Fail2ban   = ONLINE  | Internet  = ONLINE  | Ip6Tables = ONLINE    |
                                                               |  BlueTooth  = ONLINE  | Hidd      = ONLINE  | NTPD      = ONLINE    |
                                                               |  SendMail   = ONLINE  | Samba     = OFFLINE | Webmin    = ONLINE    |
                                                               |  Ethernet0  = ONLINE  | Ethernet1 = N/A     | Wlan0     = N/A       |
                                                               |                                                                     |
                                                               |  PBX in a Flash Version   = 1.7.5.6 Running *VIRTUALIZED*           |
                                                               |  FreePBX Version          = 2.8.1.4                                 |
                                                               |  Running Asterisk Version = 1.8.4                                   |
                                                               |  Asterisk Source Version  = 1.8.4                                   |
                                                               |  Dahdi Source Version     = 2.4.1.2+2.4.1                           |
                                                               |  Libpri Source Version    = 1.4.11.5                                |
                                                               |  IP Address               = 192.168.1.7 on eth0                     |
                                                               |  Operating System         = CentOS release 5.6 (Final)              |
                                                               |  Kernel Version           = 2.6.18-238.9.1.el5 - 64 Bit             |
                                                               |                                                                     |
                                                               +---------------------------------------------------------------------+

**UPDATE**

I tried change the SIP trunk configuration of the vitelity trunk away from the above default PIAF settings and instead used their recommended settings. End result is the same. Here are the settings recommended from their website:

type=friend
dtmfmode=auto
host=inbound27.vitelity.net
context=inbound
username=MYUSERNAME
secret=MUSUPERSECRETPASSWORD
allow=all
insecure=very
nat=yes

 

[nb1301]

I have the same exact problem, but it's only when dialing to certain numbers/fax machines. I have not had a problem sending a test fax to HP, and sending faxes to both numbers on faxtoy. I can send and receive to/from the HP test fax number successfully. Incoming has been somewhat reliable from other local numbers.

However, sending faxes to the only number I need to periodically send documents to does not work. It worked sparingly in 1.4, but it does not work at all in 1.8. If I attempt to send a fax via ATA , I receive the same issues you do, and line busy errors. If I try to fax with hylafax/avantfax I encounter errors like "Busy Signal Detected", "Unspecified Transmit Phase" "Failure to train remote machine" and "Failure to receive silence." I have no idea what is causing this, and it changes almost every time.

 

[jason_m]

I've seen this problem when certain carriers force t.38 upon detection of a fax. The proxy tries to re-invite the audio, but when the sip client doesn't support the t.38 codec, the proxy then drops the call. See if you can bring it up with your provider and sometimes they can disable it, but sometimes the wholesale carriers are forcing it so the problem exchange can sometimes be re-routed.

 

[wardmundy]

Vitelity does not support faxing on their standard VoIP trunks. They do have fax trunks separately available.

 

[nb1301]

Thanks for the clarification. I picked up a voip.ms account, configured the trunk, and everything worked immediately. I have been able to send faxes to numbers I was not able to before.