SyncML support (supported by e.g. Motorola EZX and many other phones
and devices, for example the SyncML server Sync4j). SyncML also allows you to
do remote connection of two MultiSync programs via an encrypted connection
over the net.

MultiSync is a free modular program to synchronize calendars, addressbooks
and other PIM data between programs on your computer and other computers,
mobile devices, PDAs or cell phones. MultiSync works on any Gnome platform,
such as Linux.