A former housmate of mine had a great solution:

Whenver a telemarketer would call, he would say, "Just a minute", and in loud enough voice for the telmarketer to hear he would shout, "[Insert name telemarker asked for here], pick up the phone!!". He would then put the phone down loudly on the counter, wait a few minutes, pick it up and ask, "Did [name] pick up yet?" to the offensive telemarketer. When he got the answer "no", he'd yell for "whoever" to pick up the phone even louder...

He would repeat this sequence two or three times for our amusement until the telemarketer would hang up, frustrated that HIS time had been wasted!!

Great laughs by all in the house.