I actually had a problem with this a couple days ago (and obviously in the past). I was busy at the time and muffed it, but I tried to get in the usual spiel I have for such people which boils down to this: Let them know that their product/service is not necessary for you.
In this recent case, the caller was asking for donations for a veterans group. I attempted to say the following:
I appreciate the opportunity, but I've already made donations to similar groups within the past year. I'm not interested in donating at the present time. Thank you for your time.
This is almost always true. I'd be more inclined to donate if I hadn't already donated to that subset of group, but if I have, I'm probably not interested.
If it's a for-profit business group, things can be different. I'm less likely to be nice than I would be to a charitable organization. I like to tell them that I simply don't need what they're selling. For instance, if a telemarketing cold caller were to call me selling a magazine subscription, I could say either
I already have a magazine subscription regarding that topic. I'm not interested.
I'm sorry, but I'm not interested in that subject.
Most of the time, I find I can be truthful by saying that my need is already satisfied, but if I'm not comfortable with lying - and sometimes I am - I'll simply say
I'm not interested in [your product]. Thank you.
Any of the above statements are succeeded by a brief pause to let them say something. If they say something like "Okay, thank you", then I'll end the call. If they continue the pitch, I'll hang up with a "Sorry, not interested". This is what I failed to do a couple days ago. Vylix suggested adding "I'm hanging up now" in this second case, which is more final and possibly a little nicer than just hanging up.
Basically, in cases of cold calling, I end up doing the following:
- Letting them know that I don't need what they're selling and will not need it in the future (in case they try to put me on a mailing list or something).
- Thanking them for their time, if they aren't too annoying. I find that this can be final without being rude. I especially try to be nicer to folks from charitable or non-profit organizations. Yes, cold calling is generally rude, but some callers have good intentions. Others don't.
- Ending the conversation. I messed up that call a couple days ago because I let them keep talking. That was A Very Bad Move. Cold calling (and telemarketing) is a case where it may be important to have the last word.