Asterisk callback custom script

I need sample of callback script for Asterisk using PHP. It should include: 1) AMI or call file function to make callback 2) Calls will be made only using SIP trunks without registration. Call flow: 1) A calls Asterisk, enters destination using DTMF (this is already done using IVR/AGI php script) 2) Asterisk drops call and calls A back (usig AMI or call file) 3) When A answers Asterisk calls B Quite regular case.