> Mr. Portman is correct ; DOV using 56K channels works just spiffy under
> b8 when using either synchronous connection or PPP translations. I haven't
> played around with it sufficiently to get multi-point to work. However,
> this raises a significant question that should be asked:
>
> Why, oh why, does the PM3 not support v.120 on the voice BC?
I'm going to take a WAG here. V.120 is commonly an ISDN only protocol.
Since the call coming in is not a true ISDN call, the V.120 code doesn't
get kicked in.
The clever hack they are using, having the HDLC and modem cards "fight it
out" to get the call, probably cannot support a 3 way negotiation.
My guesses as to how calls are routed. Feel free to correct me if I'm
wrong.
Scenario 1:
V.120 ISDN call comes in, gets routed directly to HDLC engine. HDLC engine
autodetects V.120 framing and switches it on.
Scenario 2:
Synch ISDN call comes in, gets routed directly to HDLC engine. HDLC frames
are (quickly) detected and synch PPP mode is set.
Scenario 3:
Voice modem call comes in, gets routed to modem card and HDLC engine at
the same time. HDLC engine times out after short pause (100-300 ms?), and
modem card continues to negotiate analog carrier.
Scenario 4:
DOV call comes in, (looks just like 3 so far), gets routed to modem card
and HDLC engine. HDLC engine quickly detects HDLC frames and tells the
modem card to get lost. At this point, detection is finished, and the
protocol is set as synch PPP (HDLC).
The code to look for three possible cases is easily 4 times as complex as
the code to look for two possible cases.
My WAG is that once the HDLC engine has a match, it's not programmed to go
any further.
Comments, MZ?
> >From my knowledge of ISDN, there seems like there is no sound technical
> reason for it. It's already build into the code base since it's supported
> for data BC's. Did the engineers just forget to include it?
Hmm. It's probably not easy. :-)
Later,
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