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isdn4k-utils-doc-3.12-17.mga5.x86_64.rpm

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<H2><A NAME="ttyI"></A> <A NAME="s15">15.</A> <A HREF="i4lfaq.html#toc15">ttyI: Configuration of the ttyI* devices (`Modem emulation') </A></H2>

<H2><A NAME="ttyI_nomodem"></A> <A NAME="ss15.1">15.1</A> <A HREF="i4lfaq.html#toc15.1">ttyI_nomodem: Don't the ttyI* devices emulate an analog modem? </A>
</H2>

<P>No! The ttyI* devices just offer a similar communication interface, where
all commands are started with <EM>AT</EM>. This makes it easy to reuse software
that was written to communicate with a modem. <B>Communication with a remote
analog modem is not possible via the ttyI* devices!</B> The real communication
happens in digital, not analog form.</P>

<H2><A NAME="ttyI_dev"></A> <A NAME="ss15.2">15.2</A> <A HREF="i4lfaq.html#toc15.2">ttyI_dev: Which devices should I use for calls out or calls in? </A>
</H2>

<P>Only the ttyI* devices should be used. The cui* devices are created
only for reasons of compatibility. Now that there is mgetty, there is not
reason to use the cui* devices any longer. If they are used, locking will
not work correctly (several programs could simultaneously attempt to use
the same device).</P>

<H2><A NAME="ttyI_hdlc"></A> <A NAME="ss15.3">15.3</A> <A HREF="i4lfaq.html#toc15.3">ttyI_hdlc: How to I switch the modem emulation from X.75 to HDLC? </A>
</H2>

<P>With the option S14=3; for example &quot;ATS14=3&quot;.</P>

<H2><A NAME="ttyI_uucp"></A> <A NAME="ss15.4">15.4</A> <A HREF="i4lfaq.html#toc15.4">ttyI_uucp: How can I poll with Taylor-UUCP using isdn4linux? </A>
</H2>

<P>As usual, the same as with serial interfaces. Simply use /dev/ttyI* as the
device, as the init string for the modem emulation you have to set the
correct MSN or EAZ with &quot;AT&amp;Emsn/eaz&quot;.</P>

<H2><A NAME="ttyI_speed"></A> <A NAME="ss15.5">15.5</A> <A HREF="i4lfaq.html#toc15.5">ttyI_speed: What speed should I set for the ttyI* devices? </A>
</H2>

<P>It doesn't matter. The driver internally always uses the full speed that
ISDN offers. This is also given in the connect string.</P>

<H2><A NAME="ttyI_max"></A> <A NAME="ss15.6">15.6</A> <A HREF="i4lfaq.html#toc15.6">ttyI_max: How many devices are the maximum supported number? </A>
</H2>

<P>The maximum can be set by configuring ISDN_MAX at compile time.
Currently, it is set to 64 by default, which means that up to 64
ttyI devices are supported.</P>


<H2><A NAME="ttyI_nocarrier"></A> <A NAME="ss15.7">15.7</A> <A HREF="i4lfaq.html#toc15.7">ttyI_nocarrier: When I dial with &quot;ATD.....&quot; I always get a &quot;NO CARRIER&quot;. </A>
</H2>

<P>Before dialing, you have to enter &quot;AT&amp;E123456&quot; (if 123456 is your
own MSN; with 1TR6 give the one-digit EAZ).</P>


<H2><A NAME="ttyI_noincall"></A> <A NAME="ss15.8">15.8</A> <A HREF="i4lfaq.html#toc15.8">ttyI_noincall: My ttyI* device/pppd does not recognize an incoming call. </A>
</H2>

<P>Probably you did not tell the modem emulation with <CODE>AT&amp;E</CODE> which
MSN to use. For example, use <CODE>AT&amp;E123456</CODE>; if your MSN is 123456.</P>
<P>Please also note that only one application using the ttyI* devices will
receive a ring for a particular MSN. Which will ring is selected by a loop
over all ttyI* devices. A device is selected based on whether its
parameters match (protocol, MSN) and whether it is currently not involved
with another call. Therefore it does not make sense for multiple applications
to register for the same MSN via the ttyI* devices, unless you want to
have load sharing between the applications.</P>

<H2><A NAME="ttyI_callphone"></A> <A NAME="ss15.9">15.9</A> <A HREF="i4lfaq.html#toc15.9">ttyI_callphone: Why can't I dial my telephone or fax from the ttyI* devices? </A>
</H2>

<P>You can. However, ISDN differentiates different services. All outgoing calls
with the ttyI* devices use the service &quot;Digital Data&quot;, which is
incompatible with telephone or fax, so the call never gets through.
Change the service recognition with the <CODE>ATS18=1</CODE> command to audio, then
you can dial your telephone or fax.</P>

<H2><A NAME="ttyI_noconnect"></A> <A NAME="ss15.10">15.10</A> <A HREF="i4lfaq.html#toc15.10">ttyI_noconnect: I can't get a connection to my ISDN mailbox/BBS. </A>
</H2>

<P>There are several possible protocol parameters. There is HDLC, there is
X.75 and there are several possible block sizes with X.75. You can tell
the modem emulation about the block size with <CODE>AT&amp;</CODE>. Mostly
used is a block size of 2048 byte: <CODE>AT&amp;B2048</CODE>.</P>

<H2><A NAME="ttyI_forcehangup"></A> <A NAME="ss15.11">15.11</A> <A HREF="i4lfaq.html#toc15.11">ttyI_forcehangup: My modem emulation hangs. How can I force my card to hang up? </A>
</H2>

<P>If there is really no process using your modem emulation any more, try:
<HR>
<PRE>
cu -l /dev/ttyI0 dir
+++
ath0
~.
</PRE>
<HR>

Before and after &quot;+++&quot; you have to wait for a second, otherwise the
modem emulation won't recognize it as the escape sequence (like a normal modem).
Watch out for processes that (with &quot;ps -ax&quot;) have something like
&quot;I0&quot; or &quot;I1&quot; in the second column, they have an ISDN
terminal as their controlling terminal. You may have to kill them with kill.</P>

<H2><A NAME="ttyI_channelclosed"></A> <A NAME="ss15.12">15.12</A> <A HREF="i4lfaq.html#toc15.12">ttyI_channelclosed: During a tty connection, I get a message from the kernel: &quot;teles_writebuf: channel not open&quot;. Then no more input is accepted for this connection. </A>
</H2>

<P>Can happen when the partner cannot handle the large frames from i4l and simply
closes the B channel during the transfer. Try making the frames smaller with
AT&amp;B512.</P>

<H2><A NAME="ttyI_x75uucp"></A> <A NAME="ss15.13">15.13</A> <A HREF="i4lfaq.html#toc15.13">ttyI_x75uucp: When I use UUCP with X.75, I always get transfer errors! </A>
</H2>

<P>Andreas Gutzwiller <CODE>
<A HREF="mailto:andy@hippo.proxyon.imp.com">andy@hippo.proxyon.imp.com</A></CODE> wrote on 5 Dec 1996:
<BLOCKQUOTE>
I had to use the following settings, otherwise I only had errors.
# Prot
protocol-parameter g packet-size 512
protocol-parameter g short-packets y
protocol-parameter g window 7
protocol-parameter g remote-window 7
protocol-parameter v packet-size 512
Now with large packets I can get ca 7300 cps.
</BLOCKQUOTE>

Holger Burbach <CODE>
<A HREF="mailto:holly@cthulhu.pfalz.de">holly@cthulhu.pfalz.de</A></CODE> on 5 Feb 1997 had another
solution:
<BLOCKQUOTE>
I have several XP users who poll without any problems. I did
the following: First I set the send packet size for ttyI?
to 1024 (&quot;AT&amp;B1024&quot;) and then set the packet size for the
g protocol in UUCP:
protocol-parameter g packet-size 2048
protocol-parameter g remote-packet-size 0
As I said, it works fine..
</BLOCKQUOTE>
</P>



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