Re: [hylafax-users] Multitech MultimodemDID & Voltage ?

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

On 2004.06.07 08:32 Bill Culpepper wrote:
> Anybody ever have trouble with voltage measured at the CO on these 
> analog DID trunks?
>
> SBC tells me they are only showing 3V on tip; 42 on tip˚ and no 
> ground.  Have Bell tech coming out this PM to check on site. They 
> have worked intermittently; in fact worked like a champ on Friday, 
> but came in this AM and Bell CO had detected errors and busied out 
> the lines.  Did switch wires in the wall jack just in case original 
> tech had them backwards; line busied out.
>
> Thanks for any help or stories that you have.

One thing to note about these modems is that the default setting is to 
have the DID "busied out".  Thus, it requires the modem to be 
initialized before it can be ready... unless you save the configuration 
using AT&W0.

Thus, if your modems are sitting idle and experience a power outage but 
the server does not, then the DID lines will be busied out until 
faxgetty is restarted; the server won't know of the problem - you'll 
have to hear it first from people calling you on the phone telling you 
that your lines are not working.  If you're having power problems, then 
maybe this is a factor.

One thing to keep in mind with these DID modems is that we only really 
want DID enabled for incoming calls, and the DID should not be enabled 
during the initialization process.  That's why I made the 
ModemReadyCmds config option you'll see on:

http://bugs.hylafax.org/bugzilla/show_bug.cgi?id=374

So what I did was to move the modem initialization commands from 
ModemResetCmds to ModemReadyCmds, set ModemResetCmds to *disable* DID 
("ModemResetCmds: AT*DS0"), and used AT&W0 to write the idle 
configuration into the modem (run faxgetty, wait for it to initialize 
and then kill it, then run 'minicom -o' and type AT&W0<cr>, you won't 
see the echo - you'll do this blind and see "OK", then exit minicom and 
restart faxgetty).

So there's still a remote possibility of a call coming in during a 
modem initialization after DTR has been raised but before ModemRestCmds 
is issued (there's like a 5.5-second window there by default, I think, 
which can be made to be practically nothing if ModemSoftResetCmdDelay 
and ModemResetDelay are both set to zero - it's safe on these modems).

Anyway, I'm not sure what could make the telco think that there was a 
problem with the modems.  Once I've gotten these things running myself 
I haven't had any issues since (except for a power outage which 
required me to restart faxgetty and follow the steps I've outlined).

Lee.

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