SIP or Premicell for fax?

[Drunkard #1]

SIP: POTS fax --> ATA (T.38) --> 3G router with external antenna (Telkom lines keep getting stolen) --> SIP line provider --> POTS fax

Pros:

New equipment.
Lower cost per call - not really an issue.


Cons:

Been told that T.38 is unreliable over 3G.
Untested.
R 49 pm line cost - not really an issue.


Premicell: POTS fax --> Premicell --> GSM network --> POTS fax

Pros:

Simple.
Been told it's as reliable as a wood burning stove.


Cons:

12 year old, second hand equipment.
Higher cost per call - not really an issue.

Help me decide. Thanks.

Yes, it must be a POTS fax. No, we can't use email.

 

[Hummercellc]

If you have to,

8ta 3G + Huawei B683 + External Antenna + Grandstream HT-701 (1 Port) or Grandstream HT-702 (2 Port)

I have tried it with VOX and it works 95% of the time.

You need to use G711A (alaw) codec and use T.38 pass through, disable echo cancellation and disable silence suppression.

Make sure your latency is under 100ms and your jitter is no more than 20-30ms.

Also make sure you disable SIP ALG on the Huawei device, it gives you one way audio problems.

Further more lock the router to 3G only.

I am still playing with it on my end for people with the same problem as you and need to FAX.

I tried with swicthtel once and it fails every time, VOX seem to be the only one that allows T.38 Pass Through.

If you need any settings PM me.

 

[breedenet]

If you are after fax over internet then pangea is the best option. Works everytime

 

[Drunkard #1]

If you have to,

8ta 3G + Huawei B683 + External Antenna + Grandstream HT-701 (1 Port) or Grandstream HT-702 (2 Port)

I have tried it with VOX and it works 95% of the time.

You need to use G711A (alaw) codec and use T.38 pass through, disable echo cancellation and disable silence suppression.

Make sure your latency is under 100ms and your jitter is no more than 20-30ms.

Also make sure you disable SIP ALG on the Huawei device, it gives you one way audio problems.

Further more lock the router to 3G only.

I am still playing with it on my end for people with the same problem as you and need to FAX.

I tried with swicthtel once and it fails every time, VOX seem to be the only one that allows T.38 Pass Through.

If you need any settings PM me.

Thanks, that's exactly the sort of info I wanted, although I'm still tempted to get the cheap-ass stuff from scoop. We run a B683 at the office for backup, but it's like 4 times the price. I'll probably get the kit in a few weeks time and try it out. I'll let you know.

What do you think the chances are, of getting it working via a VPN to the office's IP switchboard? Cut the VoIP provider out completely. Mmmm I'll give it a go some time.

 

[Hummercellc]

Thanks, that's exactly the sort of info I wanted, although I'm still tempted to get the cheap-ass stuff from scoop. We run a B683 at the office for backup, but it's like 4 times the price. I'll probably get the kit in a few weeks time and try it out. I'll let you know.

What do you think the chances are, of getting it working via a VPN to the office's IP switchboard? Cut the VoIP provider out completely. Mmmm I'll give it a go some time.

Best to use the Grandstream ATA's at least, the most reliable devices out there.

Also VPN should work, I currently router traffic to JHB via VPN (L2TP) and have not had a problem.
The down side to VPN is the added over head due to the MTU sitting at 1440, so you loose about 10-15% of total transfer capacity.

Just make sure if you are using any Asterisk based system you enable T.38 and set it's parameters in sip.conf file.
Because you will see "codec pass through not allowed here" in the Log and Fax's will fail.

 

[Tim the Techxpert]

Hi There,
Did some googling on the reliability of T.38 over 3G and found nothing worth reporting that it is unreliable. If therre are instances out there it probably relates to general 3G reliabillity and not the T.38 and 3G together. That sounds the simplest and easiest dolution to me.

Regards

Tim