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Increasing delay for DTMF routing info for fax

how do I make the system wait for dtmf routing information longer on the fax ports? We have it set to "DTMF(manual)" and we've tried "DTMF (telco)" and it's sometimes not waiting long enough and the fax gets dropped to the unaddressed faxes group.<br><br><br><br>


Re: Increasing delay for DTMF routing info for fax

Ok, couple things to talk about here…

Folks get confused over the “telco” and “manual” stuff a lot. It’s a little odd. The “DTMF (manual)” setting means when the port goes off hook it’ll wait a designated number of seconds to hear DTMF before playing fax tone at you. The “DTMF (telco)” setting will start playing fax tone as soon as it goes off hook. The thing to note is that BOTH settings will be listening for DTMF input for the same period of time… you can enter DTMF while the fax tone is warbling out at your and it’ll still use it to route the fax. I usually recommend “manual” just since it’s a little easier to deal with when testing it manually from a fax machine.

The time it waits to hear DTMF, the number of digits collected and a number of other types of settings are not fax server things… they’re set at the fax driver level. Unfortunately there’s no snappy GUI utility to change these settings (driver guys are not real big into friendly user interface issues... they live in dark, cold places and we tend to leave them alone...) so you have to change these in the registry. Assuming you’re using GammaLink drivers (which you are if you’re running ActiveFax) you can use the following settings to adjust these values… if you’re using Brooktrout or some other fax card, you’ll have to refer to their documentation for details, they’ll have something similar.

Open RegEdit and go to "HKLM\Software\GammaLink\gfaxcfg\Channel1\"

Add a new string key there called "gfxdtmftimeout" and give it a value of "5 10" (yes, there's a space there). The "5" is how long it'll wait (in seconds) after going off hook before it gives up waiting for DTMF and the 10 value is how long it'll wait total for all the DTMF routing information. So if at least one DTMF digit comes in within 5 seconds, it’ll wait up to 10 seconds for remaining DTMF unless the max digits or a terminator is received (see the next paragraph for that). It'll accept values for either parameter between 1 and 32,000... but I would think something like 5 and 10 are pretty reasonable there.

You need make this change for each fax channel in the registry and then reboot before it takes effect.

You can also adjust the total number of digits it looks for and the terminator if you want... in the same spot in the registry, create a new string key called "gfxdigits" with a value of "5 2048". This will look for up to 5 digits or will terminate on a "#" key (2048 is their specification for # which is the default, 0 means no terminating digit). As soon as it gets 5 digits it’ll stop and route based on that. If it gets a # it’ll stop and route on what it has. If neither of those happen, it’ll wait the full time you specified in the gfxdtmftimeout parameters above.

hope that helps...

Jeff Lindborg
Unity Product Architect
Active Voice

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