i like to say I am detective RogersThen I interrogate the caller...

i like to say I am detective Rogers

Then I interrogate the caller as a homicide has just occurred and insist that they come in to the police station so they can be interrogated further Ask them how they know the person they are calling and any personal problems they have.Progress the interrogation into more and more personal/sexual areas.

Interrupt the interrogation and yell to your pretend constable
"have you traced that call yet constable "

Then finally tell them that they will be required to be a witness / suspect and are required to attend the police station and no excuse will be accepted.There passport will be confiscated until they turn up.Then hang up

hahhahah