KMobileTools is a nice KDE-based application that allows to control mobile phones with your PC. It handles full SMS control, dialing calls, phonebook, and phone status monitoring. It's also integrated with the KDE environment, so it can be embedd in Kontact, or import/export from and to KAddressBook. It has been tested on Motorola, Nokia, Siemens, Sony Ericsson and LG mobile phones. Anyway each AT Command compliant device should be well supported.