If you want to send but not receive SMS messages, the Web gateway clients on CPAN (such as Net::SMS::Web or WWW::SMS) or scripts on Perl Monks that others have recommended will do fine.

If you have a spare phone and SIM card and need something more advanced, maybe because you want to receive messages as well as send, or you want delivery reports, or you don't trust the reliability of Web gateways, look into GSM::SMS or Gnokii which has a Perl interface.

If you really want a complete SMS server, there's nothing I'm aware of in Perl that would be adequate, but you might find Kannel useful.