[cisco-nas] dial-strings with embedded pauses

[Aaron Leonard]

Hi Kevin,

These "embedded pauses" are what we call "dial modifiers" when used with
digital modems.

I.e. your 3845 is connected to the circuit network via ISDN PRI.  So it
signals addresses via Q.931 messages, not via some kind of DTMF.

So if your modem dials out with ATDT 5551234, this does not trigger
"5551234" to to be sent as DTMF tones ... rather "5551234" goes out as
the Called Party Number in the Q.931 SETUP message that is sent to your
switch.  This works extremely quickly and reliably.

However, as you have found, pure ISDN Q.931 signaling won't do if you
need to go thru some kind of secondary dialtone / IVR type stuff - there
the dialing modem really does need to send out some DTMF.  I.e. the
router *first* needs to send some digits in Q.931 to establish the
initial call leg, then needs to switch into DTMF and send the rest of
the digits (possibly with interspersed pauses, waits for incoming dial
tone etc.) inband.

Our Dial Modifiers feature, which works with MICA and NextPort modems,
supports this.  You can see documentation on the AS5300 MICA flavor, at
http://www.cisco.com/en/US/docs/routers/access/modem/portware/mica/portware/release/note/dtdialmo.html
.

For the PVDM2-DM modems, dial modifier support hasn't been added till
very recently:

CSCsj21185    %PVDM2_DM-3-CSM_ERROR: DTMF NAK, line 723 by commas in
dial string ,
 - this implemented support for the comma dial modifier in 12.4(17.6)T
CSCsm58210    Need Jebbin PVDMx-xxDM to support W dial modifier
 - this implemented support for the W ("wait for dial tone") modifier in
12.4(21.2)T

So, you should upgrade to an IOS version that has these features, e.g.
12.4(22)T1 or 12.4(24)T, and see whether the modems now work as desired.

Cheers,

Aaron

------------------------------------------------------------------------

Roth, Kevin P. wrote:
> I have a Cisco 3845 services router setup to do dial-on-demand routing
> using a dialer interface with a "dialer map ip" command to configure the
> phone number.  I'm using PVDM2-24DM digital modem cards with T1 PRI
> lines for the POTS connectivity, and am connecting to Cisco 1841 devices
> out "in the field".
>
> One of my 1841 devices is behind a PBX system, with an extension number.
> To dial it from a desk phone, I dial the main office phone, and then
> when the automated attendant picks up the line I press an extension
> number (e.g. 123) on my phone keypad.  At that point the call is passed
> to the extension where the 1841 is plugged in, I can hear a ring or two,
> and then the 1841 picks up the line and I hear "modem tones".
>
> In an older system which is just using Motorola modems, we can dial into
> a site with a similar configuration by using a dialing string like this:
> 	ATDT 1-333-555-1212,,,,,123,,123,,123
> where the comma's cause the dialing modem to pause in the right places
> so that one of the 123's will occur when the automated attendant is
> listening, and the connection goes through fine.
>
> I can't find an equivalent "pause" character that works in the Cisco
> 3845.  We are configuring these connections using commands like "dialer
> map ip 1.2.3.4 1-333-555-1212".  I've tried using a left-angle-bracket
> (<) as suggested in a few "dialer string" commands.  If I turn on dialer
> or chat debugging, it appears that any time I have extra characters
> after the actual phone number, the carrier drops almost immediately (1-2
> seconds) following the completion of the ATDT command, and the
> connection times out.
>
> I've also attempted (though perhaps incorrectly) to use modem-script
> and/or system-script commands along with chat-scripts to try and insert
> pauses using "\d" strings.  
>
> If I dial an 1841 with a dedicated phone number, everything works fine,
> so I think the only problem is that I can't figure out how to insert
> "pauses" into the dial-string for the PVDM2 digital modems.
>
> Can anyone point me towards the right configuration to use in this case?
> Is this even possible?
>
> Thanks,
> - Kevin
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