[Help]How to make multiple calls

I had written a php code which uses AMI to call out the numbers stored in the Mysql database. I have four external numbers in the DB. I can make calls to only the first two numbers in the DB. How can I make call to all the numbers.
Also how to get information from asterisk if one number is dialed so as to make call to the next number after dialing the first number. Or I can dial all the numbers simultaneously.
Thanks in advance