A Phone call between husband and Wife.

Husband and his wife agreed that anytime they want to have sex, they will call it 'phone call' so that the kids will not understand.  One day, the husband was horny and sent his son to tell his mother that he wants to make a phone call .. Mother replied: Tell your father, the network is bad today. Husband: tell your Mother that if there is no network at home I will go to the 'public phone' wife replies: tell him that if he dare goes to a Public phone then I will open a business centre at  home