Faxing

find out what method of T38 they use... btw T38 isnt a standard (should be but isnt) so theres lots of 'flexibility' to not work with other equipment. Dont get me started. Faxing is and always will be the bane of your productivity.

I found these settings someone had put together but hadn't tried them yet.

|SIP|

RTP Packet Size: 0.020 from 0.030

|Line 1| and |Line2|

* Preferred Codec: G711u

* Use Pref Codec Only: yes from no

* Silence Supp Enable: no

* Silence Threshold: medium

* Echo Canc Enable: no from yes

* Echo Canc Adapt Enable: no from yes

* Echo Supp Enable: no from yes

* FAX CED Detect Enable: yes

* FAX CNG Detect Enable: yes

* FAX Passthru Codec: G711u

* FAX Codec Symmetric: no from yes

* FAX Passthru Method: None from NSE

* FAX Process NSE: no from yes

changing from 30ms per packet to 20ms per packet is always a good thing, I still cant believe linksys defaults to 30ms packets on all their gear when the evidence is quite clear that

that does not enable t38, thats how you do in-band g711 faxing (you also must make sure fax machine is set to 9600 or 14400 but no faster). Make sure you've updated your firmware to 5.2.5 or higher.

your g711 faxing checklist

* Network jitter buffer: very high

* Jitter buffer adjustment: disable

* Call Waiting: no

* 3 Way Calling: no

* Echo Canceller: no

* Silence suppression: no

* Preferred Codec: G711u

* FAX enable T38: no

* Use pref. codec only: yes

you need to find out what method the provider uses for T38 (FEC or redundancy method)

here is a commonly successful T38 faxing profile:

JITTER BUFFER

These settings allow the ATA to use the maximum jitter buffer so that it can handle the worse network jitter possible.

• Network Jitter Level: extremely high

• Jitter Buffer Adjustment: disable

TYPICAL FAX SETTINGS

These settings adjust the echo cancellation and codec settings.

• FAX CED Detect Enable: yes

• FAX CNG Detect Enable: yes

• FAX Passthru Codec: G711u

• FAX Codec Symmetric: yes

• FAX Process NSE: yes

• FAX Enable T38: yes

• FAX T38 Redundancy: 1 <-- this sets the number of duplicate frames sent

OTHER SETTINGS

• FAX Passthru Method: ReINVITE

• FAX Disable ECAN: yes

• FAX Tone Detect Mode: callee only <-- some providers require this, trial and error is suggested to determine your best setting.

try those setting as still can not get it to work.

please help

what version of asterisk? Theres a bug thread that its apparently not working in 1.6.0.10 and higher

https://issues.asterisk.org/view.php?id=15586

I have the same problem. I use linksys 2102 ATA and my provides have Cisco gateway with T.38 enabled. I didn't manage to send any fax at all. I tried many different versions of asterisk (1.4 and 1.6) and every version seems to act different way.

Right now I use 1.4.26.1. In sip debug logs it looks that T.38 negotiation was successfull, later I receive SIP BYE packet from provider and the call si hangup but no fax is sent.

I can provide the sip debug file if needed.

thanks in advance for any help.

Peter

We are using Linksys SPA-2102 ver 5.2.10 and Thirdlane MTE Centos 5.2 and asterisk 1.6.06

we can not get even 1 fax to work

please help

The first thing you should do is ensure the fax machine you are testing with is set to send and receive at 9600 baud (or 12K and/or 14.4K if you enabled it during compilation), if the machine is trying v.34bis it may not back down. If you cannot set the baud rate, it is a poor choice of a test machine.

Then if that doesn't work you should almost always be able to force a passthrough with g711 (the default), again, using 9600 baud.

If you are using a cisco gateway and a PRI you should never have issues with the NSE passthrough at 9600 unless the PRI is taking errors or timing slips, or LAN errors. Least I don't.

Every customer that I can configure their machine to 9600 baud, I never have issues with. The ones that I can't, they pretty much call me every day. To which I have to say, sorry but your fancy fax machine sucks on my service, or vice-versa.

what settings do you recommend for using a linksys SPA-2102?

what settings do we set the outbound route (do we enable NAT)?

My 2 cents worth....

We wasted 100 of hours with Linksys SPA-2102 for faxing. Someone suggested using Adtran. We bought TA904 as a testing unit, deployed that at a customer site. 2 years in production, not even a single issue.

If you need faxing for business users, Adtran is the way to go.

OJ

Do you run a T1 to every customer and break out an FXS port for fax using the TA904?

I spent many days with linksys 2102 and zyxel ATA for T.38 faxing and it never worked properly with asterisk. I reported issue to asterisk bug tracker it was assigned to Kevin P. Fleming. I was with contact with him for about 2-3 weeks on daily basis. He made quite a few patches for me but it never worked properly.

After that I installed FreeSwitch. Set it up in couple of hours and it just worked straight away...

Now I use FreeSwitch as gateway for my Thirdlane MTE. All sip trunks from provider are registered on FreeSwitch. All fax DIDs are routed to local extensions on Freeswitch and all the other DIDs are routed to Thirdlane box. This works for me.

Peter

You can use Adtran that way too. I am running it over public internet. All the faxes go through my Hosted TL MTE box. My SIP provider also supports T.38.

the 904 is a t1 only device obviously.. the model for an ethernet delivered internet connection would be a 908e, 916e, or 924e. Those are quite pricey if you haven't looked into them. BTW don't use fragmentation and interleave on the MPPP or DTMF will fail at a very high rate. I have a bug report in with digium to hopefully fix it.

My faxing experiences with 908's is mixed. In-audio (g711) faxing seemed to work well but T.38 didnt work as well with the AttraFax gateway (attractel t.38 gateway for asterisk). I could send T.38 to the adtran 100% success but when sending from the adtran to the gateway I would be lucky to get 15% success rate.

However, recently I had a customer's fax machine die. This was a customer using the Adtran 916e for g711 faxing for months without issue. So they went and bought a Brother (which does not let you set the speed); it was failing 100%. I had them exchange it for an HP M1522nf multifunction laser machine for the same price ($400). The HP kept failing saying 'could not detect fax'. The HP worked fine on a plain POTS line but would not handshake on the Adtran. We took our fax machine to the customers office, a 10yr old Xerox workcenter 745 pro. Our Xerox worked 100% without a single issue, and yet the HP couldn't even conduct a fax handshake on the same line. We tried increasing the gain, decreasing the gain, nothing helped. We finally had to order a pots line for this customer and eat the cost since we really can't be in the business of telling a customer which fax machines they can and cannot use.

I guess the moral to this story is that every time you think you have a strangle hold on the faxing situation, it can turn around and bite you on in the ass.

Adtran 2nd generation 904's actually have two T1s and an ethernet port.

the 2nd port is for PRI, the ethernet is for the LAN. Are you not using these as a full fledged router?

Inbound fax we are sending to email via PDF - so that is not an issue

Oubound faxing is where all our problems are.

We are using TL MTE.

We terminate with a couple of suppliers via public IP and they support T.38 and we have had no luck.

We understand that every fax machine has different issues, but it would be nice that even 1 fax would work.

Erik,

I have never used PRI on Adtran and yes I am using these as full fledged router.