User management

I feel user managerment in asterik system is dificult. Every time I and a iax user. I have to add the user info and phone number in iax.conf and extensions.conf. I want to know if there are some easy way? For example,
I can add the user info in database, and the asterisk to read the database automaticly.

the wiki is your friend.

voip-info.org/wiki-Asterisk+RealTime

or maybe look at one of the many GUIs available

voip-info.org/wiki-Asterisk+GUI