Ringtones & Asterisk charging

Hi all

Can anyone explain \clarify for me the start of biiling on ASterisk ??

My provider start charging me on the 200 Ok
and ASterisk start charging my employee on the 200Ok ,after being relayed from Provider to the employee

i am receiving a 1-3 sec delay between provider 200Ok and my 200Ok to the employee extension

i want to fix this but :

  1. i saw some posts about the " r " ,but if i used this parameter ; what will happens if i keep sending ringing to the customer, and the provider replied (for example) with 480 unavailable?

  2. Another mentioned to fake 3 ringtones , to the employee, and then start an empty voice (open stream-channel on employee) ,until the Provider answer my call

is there anyway to overcome these 1-3 sec ??
some of you might say this is not important ,but 1-3sec ,over 1000 number ,for each call made is something to look at .

thanks in Advanced,