I don't like being rude but honestly, you end up being rude.....
Things I have done in the past...
1) If you have toddlers, simply hand the phone to them...
2) Pretend you are hard of hearing, and keep asking them to speak louder... when they start yelling ( and the people in the cubes around them get real quiet ) laugh hysterically and hang up.
3) Tell them business hours are monday thru friday, 9 am to 5 pm, and to call you back then.
4) Make up your own language, and speak that language to them.
5) Tell them to speak english, even if they are.
6) Just set the phone down on the counter, and go back every 5 minutes until they hang up.
these will at least allow you to have a little fun
Someone interrupts YOUR life by calling YOUR phone, on YOUR line, in YOUR home, on YOUR time, to do THEIR business and YOU are worried about being rude?!?!?!