Google allow Android users to backup some parts of their phone on their Google account and in case you do a full phone reset, it restores your data back. However, it does not create a backup of your call logs.
Android, by default, logs your last 500 calls. There is an app in the Android Market to help backup and restore your call logs on another phone or after a full reset. A very small app, but very useful.
Call Logs Backup & Restore is a free app that lets you do exactly what it says to. It creates a backup of your call logs and you can easily restore them back later on the same phone or a new phone.
I tried this between my Google Nexus S and a Samsung Galaxy S II – it worked perfect! Install the app from the Android Market. Then in the app, hit tap the ‘Backup’ button to start the backup process. The backup process could never be this easy!