Telemarketers, fundraisers, scammers. While they irritate most of us, especially the overly persistent talkers, they are probably just out of options and trying their best to support their family - and, of course, they are people loved by God too. While they are hung up on and abused all day, think, what would Jesus do if he answered a telemarketer call?
How about spending some time coming up with a script and a prayer for these different callers. eg. for a fundraiser "I really admire what you're raising money for, I don't have much money to be able to contribute myself, but may I pray for you and your organization?" Get the callers name and include it in your prayer.