the phone call

A husband and wife agreed that anytime they want to have s*x,they will call it PHONE-CALL so that the kids will not decode.One day, the husband sent his son to tell mum that he wanted to make a PHONE-CALL.Mum replies, tell your dad that network is very busy today.
Husband replies, tell your mum that if network is busy @ home,I will go to a public phone boot.Wife replies, tell your dad that if he dares, I will open a business center...