Fax machine into ipdomain using G729 compression

[Elandryl]

Hi,

We are using ipdomain for each sites with g729 compression over WAN links.
The problem is for fax machine on SLI card.

The call isn't connected directly to local PSTN but throught WAN then E1 link on the main site.
So the call is considered as an extra domain call and compressed.

Using the E1's main site the fax cannot connect and return error :
"END TO END INFO TRANSMISSION IMPOSSIBLE"
If we force to use local PSTN (we have backup link on site) the fax works fine.
Using an other backup link on an other site same issue as main site.

So my first guess is the codec.

My problem is that i need to use g729 codec over WAN for phones and i'm searching how to make this configuration.

I look on fax/modem transparency but it seems that we must configure the extra domain to no compression ...

If you have any tricks !

Thanks for reading

[tot3nkopf]

Try to configure a domain only for fax machine IP without compression. In this way you use g711 only for fax and g729 for all the other phones.

[Elandryl]

hi tot3nkopf,

My fax is analog, not ip, connected to a SLI board.
So my fax is in my GD domain right ?

I'm quite sure i don't understand what you mean...

[tot3nkopf]

hi tot3nkopf,

My fax is analog, not ip, connected to a SLI board.
So my fax is in my GD domain right ?

I'm quite sure i don't understand what you mean...

Sorry thought about IP fax (audiocodes or so).

[Elandryl]

ok no problem

[Konstantinos.E]

hello

if you route the call of the fax to a ip user in the remote site and then on dynamic user state forward on the fax maybe the gd will realize that has to decompress the call...

just a thought....

[krzysioD]

Put a mgr managment of type for this SLI: analog specific type -> FAX.
Should work, i've done it many times even for analog modems, just managment mode to 'modem' speeds are not so big as v.34, but for some strange modem applications like banking or authorization of credit cards, it's sufficient.

[oliveira_Arthur]

I have same problem. ISDN link is on MG 1 and Fax sets are in MG 4. Fax works only if Fax/Modem transparency is true and no compression.

[Elandryl]

Yes exactly we may need to activate the fax/modem transparency but the most important is the compression.

Fax doesn't like G729 at all !

[krzysioD]

No, fax likes if engineers read the docs, it was said in docs what you need to have a fax / modem working between two IP MGs.