Gammu (formerly known as MyGnokii2) is a cellular manager for various mobile phones/modems. It supports a wide variety of Nokia, Symbian, and AT devices (Siemens, Alcatel, Falcom, WaveCom, IPAQ, Samsung, SE, and others) over cables, infrared, or BlueTooth. It contains libraries with functions for ringtones, phonebook, SMS, logos, WAP, date/time, alarm, calls, and more (used by external applications like Wammu). It also includes a command line utility that can make many things (including backups)...

Wammu is mobile phone manager running on Linux, Windows and possibly other platforms, where Gammu and wxPython works. The communication is made by Gammu library.

KMobileTools is an OpenSource project (GPL2 license) that aims to be a complete management system for mobile phones.
It's written in C++ using Qt and KDE libraries. It's using KParts technology, so it can be embedd in every application (like in Kontact), it can read and write KDE AddressBook, full import/export, read and write SMS, export them in KMail, and much more. All this depending on your phone capabilities, of course.

python-gammu is a set of Python bindings for Gammu, the GSM mobile manager for various cellular phones. It can work with any phone that Gammu supports, including many models by Nokia, Siemens, and Alcatel.

Gnome front end to gammu software