From: mc/G=Brad/S=Hicks/OU=0205925@mhs.attmail.com
Newsgroups: comp.dcom.telecom
Subject: Re: How to Trigger a Pager From a Modem
Date: 12 Aug 92 16:09:00 GMT
Organization: TELECOM Digest
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@eecs.nwu.edu
X-Telecom-Digest: Volume 12, Issue 626, Message 13 of 15

pfalstad@phoenix.princeton.edu (Paul Falstad) asked what to enter at
the ID= prompt when calling a paging vendor via a modem.
 
The protocol for this is the IXO/TAP protocol, and some source code I
wrote for dealing with it is in the Telecom archives.  The short
answer:
 
IF YOUR PAGING VENDOR HAS NOT DISABLED THIS FEATURE: Enter just the
letter "M", then a carriage return.  This signals the paging system
that this is a manual entry.  It will then prompt you for the pager id
and the message.
 
Cybertel, our paging vendor, has threatened to turn this feature off
because they claim it ties up the modems for too long, while people
dither over what text message to send.  If your paging vendor does not
support manual mode, then at the ID= prompt, you send <ESC> followed
by a logon ID, followed by <CR>.  I gather that the common default is
PG1; I've also heard of PG, PG0 (zero), and PG0000 (four zeros).
 
They will either send you back <CR><ACK><CR> or <CR><NAK><CR>,
depending on whether or not it's a valid logon ID.  Then comes the
tricky part.  You send them a pre-formatted message packet.  The
content of the message packet is:
 
 <STX>PagerID<CR>Message<CR><ETX>checksum<CR>
 
PagerID is all-numeric, eight digits or less, and some systems require
it to be left-padded with zeros to eight digits.  Message is any
string of up to 120 characters (on some systems, up to 240).  Checksum
is a three-byte hexadecimal representation of the numeric checksum of
everything from <STX> to <ETX>, inclusive, with A=":", B=";", C="<",
D="=", E=">", and F="?".  (In other words, the next six ASCII
characters after "9".)  After you send this packet, you'll get back
either ACK or NAK.
 
The paging software can send back lengthy comments or error text any
time it likes, but you're pretty much supposed to ignore everything
but the ACK or NAK.  If I get a NAK, what I do is look through
everything from when I sent my packet to when they quieted down for
any line ending in <CR> that is over 5 characters, and assume that
that's the error message to show the user.  The most common two are,
of course, invalid pager id and bad checksum.  Oh yeah, and any time
they're going to hang up on you, they're supposed to send
<CR><ESC><EOT><CR> first.
 
One annoying feature of Cybertel's system is that they do NOT <NAK> an
alphanumeric message sent to a numeric-only pager.
 
This is a horrible over-simplification of a complex protocol that also
permits multiple packets to the same address, and messages to multiple
pagers in the same session.  You really should consult the IXO/TAP
spec.  The only problem is, the only way I know to get a copy is to
buy a GlenAyre or similar paging system yourself; it only seems to
come with the manual.  Maybe your paging company can provide you with
a photocopy, otherwise, good luck.
 

J. Brad Hicks
Internet: mhs!mc!Brad_Hicks@attmail.com
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