How to take the backup of the phone book

Hi. You can use a free software for PocketPC such as PIM Backup (To download and read instructions (You may need to create an account in order to download the .cab file): http://forum.xda-developers.com/showthread.php?t=299705). This software will backup all your Appointments, SMS, Mails, MMS, Contacts and Tasks in a single file in less than a minute, and you can restore them also. As a second choice, you can connect your PDA to your PC/Laptop and you can syncronize your phone book with Microsoft Outlook (Using ActiveSync), that way your phonebook will be backed up to your PC. Hope this helps.

Hi U can Use SPB Back up software which is a very good softwere available in the net. It feautures are very good it will take the entire back up and partial back up is also posible in this softwere.

I try this sms transfer days ago. It could save the sms to pc and restore back to your cell phone. It get the job done well. But it just support the phone running on Windows Mobile System.
Here is the user guideline of the software.
http://www.godswmobile.com/transfer-sms-from-windows-mobile-phone-to-pc.html