FAX + VoIP - T.30 / T.38

Ok... just discovered the 2-sided discussion on Fax over IP.
Some VoIP vendors indicate they have not seen any probs over their
network,
while some integrators have said flat out it doesn't work reliably...

SO - what's been your experience with normal FAX machines
that work fine on a POTS/PSTN network...
plugging them into an analog port on a VoIP gateway,
and used across the VoIP LAN / WAN configuration ?
here -
http://www.soft-switch.org/foip.html
this is better -
http://www.cantata.com/applications/...erip/index.cfm

tnx for the feedback

Phil Schuman

I have been running analogue fax machines connected via FXS ports on a
90 site Satellite WAN (580 ms RTT) for over 3 years - they work
perfectly.

The Softswitch article is complete garbage - the guy who wrote that is
clueless.

Cisco Routers support T.38 and their own proprietary Fax protocol.
Both work with no problems. You can run 8k G.729 and run fax over it
using the command "fax rate voice" on your dial-peers. Cisco command
reference:-

>Specifies the highest possible transmission speed allowed by the voice rate. For >example, if the voice codec is G.711, fax transmission may occur up to 14,400 bps >because 14,400 bps is less than the 64-k voice rate. If the voice codec is G.729 (8k), >the fax transmission speed will be 7200 bps.

If you require fast fax transmission then with a well deisgned dial
plan, you can create sperate dial-peers for Fax calls using a 64k codec
and have your voice calls use an 8k Codec.

Check out the Cisco fax troubleshooting guide for more information on
Cisco's Fax over VoIP implementation:-

http://www.cisco.com/en/US/products/...0558500 .html

James


Phil Schuman wrote:
> Ok... just discovered the 2-sided discussion on Fax over IP.
> Some VoIP vendors indicate they have not seen any probs over their
> network,
> while some integrators have said flat out it doesn't work reliably...
>
> SO - what's been your experience with normal FAX machines
> that work fine on a POTS/PSTN network...
> plugging them into an analog port on a VoIP gateway,
> and used across the VoIP LAN / WAN configuration ?
> here -
> http://www.soft-switch.org/foip.html
> this is better -
> http://www.cantata.com/applications/...erip/index.cfm
>
> tnx for the feedback