Must be able to use any SIP provider.
You must have previous experience on creating voicemail drop software
Here is exact program flow
program will launch threads
load numbers from a txt file
load multichannel and multiple sip accounts
then starts to place calls two at a time to same number
call one times out after 1 sec
call two placed at same time goes to voicemail since line is busy
call two leaves a prerecorded voicemail and hangs up
Must be multiple threads running at same time...