> I just tested this in my PM3 which has two trunk-side CT1's (ESF/B8ZS)
> running ComOS 3.5.1b20.
Obviously, signalling differences are the key here. CT1's are quite "dumb"
in the information they can return to the switch. But, if you unplug one,
the switch will "know" not to route calls into that trunk and your other
modems should be unaffected, which is still better than POTS.
Now, with a PRI, you get a lot more call information into the PM3 even
before the call is completed.
It kind of goes like this (voice call):
Switch: "Hi, I have a voice call for you":
PM3: "Ok, I have a channel, send the call to XX (channel number)":
Switch: "Call requested for channel XX"
PM3: "Ok, answering call on channel XX"
This is a gross oversimplification, of course.
You can watch this type of conversation with "set debug isdn on" and set
console.
Later, if there are no modems free:
Switch: "Hi, I have a voice call for you":
PM3: "Oops, no more voice calls for this trunk group, try another"
If you switch is provisioned correctly, then all will work just fine.
The only time you get some a potential conflict is when someone tries
to originate a DOVBS call, since it looks and smells just like a voice
call, the PM3 may not answer it if there are no modems available.
Like this:
Switch: "Hi, I have a voice call for you":
PM3: "Oops, no more voice calls for this trunk group, try another"
If there are no trunk groups with modems available, the call will return
"busy" to the caller.
NOTE: If there is a single modem free anywhere, the call should land
somewhere and be answered, but it's really a crap shoot.
NOW: CT1 can't communicate back to the switch the way PRI can, so this
obviously won't work the same.
This is just my opinion, I could be wrong.
Later,
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Joe Portman - Alternate Access Inc. Affordable, Reliable Internet
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