Update: Sigh. You'd think I would actually read your question. Sorry.

Have you tried using answer() or passing a timeout with your dial?

If you're using Device::Modem then I think that a simple hangup() method call will do:

hangup() Does what it is supposed to do. Hang up the phone thus terminating any active call. Usage:

$ok = $modem->hangup();
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Welcome to the Monastery. You'll probably want to read up on a few of the tips for formatting questions, etc. It probably wouldn't hurt me to re-read those tips. :)