VOIP link faxes and modems

[as1981]

All,

We have a voip link between two IPO's (3.1). We can make fax calls over the link but not dial out from modems, can anyone explain why or suggest a fix? I appreciate it's a voice link but faxes contain modems so a PC based modem should also work?

Thanks

Andrew

 

[ProviderReborn]

What codec are you using between the sites?
What sort of links are you using.

ACA - IP Office Implement
ACA - IP Telephony
ACS - IP Office Implement (Aug 30th)

 

[as1981]

Thanks for your reply. I assume the codec is the compression mode on the line? It's set to auto.

I'm sorry but I am not sure what you mean about sort of link. The line entry in the IPO is a VOIP line, there are VCM cards in the IPO's and the link between the two systems is via ordinary ethernet networking with QoS. My apologies as I don't think I've answered your question.

Thanks

Andrew

 

[ProviderReborn]

Try G711 and your corect region Ie ALAW/MuLaw.

Dont forget you will need to set this both ends and please ensure your link bandwidth will cater for this, as you have not mentioned your link type.

By link I am meaning the medium to which connects the two IP Offices together? XDSL/T1/QSIG/MPLS etc

ACA - IP Office Implement
ACA - IP Telephony
ACS - IP Office Implement (Aug 30th)

 

[mforrence]

I wouldn't hold much hope for modems to work across an IP link. Remember that fax will run at 9600 baud, but you'd likely be unhappy at that modem speed. Get an analog line...
Mike

 

[as1981]

TheProvider and MForrence - Thank you both very much. To answer your questions:

TheProvider - The link bandwidth is 100mbs which carries data and voice with QoS (V-lans).
MForrence - I'll try the modem at a low speed to see if it works, I had wondered it it might. An analog had also crossd my mind, it's just a hassle as it's a rented building and so permission e.t.c. has to be sorted out.

 

[mforrence]

Remember, even to get 9600, you'll almost certainly need G711 codec enabled on both ends. If it works, and you're happy, you COULD make a new line group just for modem. Or use any number of lan-based products that give you a virtual serial connection to the modem at other end...
Mike

 

[as1981]

Thanks for all the help so far. I've swapped the codec for G711 on both systems and now when I dial out the following happens:

1. I can hear the modem dialling the number and the call appears on the call status for both systems with all the correct information.
2. For a few seconds I get short beeps from the modem and then a continuous high pitched tone at this point the call is still showing on the call status list.
3. After a few seconds of the continuous tone the call drops off the status lists but the modem continues with the continous tone.

Grateful for any ideas. I've tried at 9600 and 57600 and I get the same results.

Thanks

Andrew