Mr Paisley failed to register the trips with Parliament and later lobbied then Prime Minister David Cameron on a UN resolution concerning Sri Lanka.
The North Antrim MP is set to be suspended from Parliament for 30 days.
'Peter' a caller to the Nolan Show said that he believed there was an agenda against the DUP.
"I don't know why everybody jumps on the bandwagon here, what about the politicians here. They're getting free holidays, paid for not working. It's my tax money," the caller said.
"He's admitted that some different country paid for him and it just seems to be if you're a member of the DUP if you went into a shop and bought a packet of crisps somebody would claim you didn't pay for them.
"The DUP seems to be under a lot of scrutiny, there seems to be some kind of agenda to try and get them out of power.
Mr Nolan said that he was simply doing his job.
"There's no agenda, what are you talking about. This is a prominent politician who has apologised profusely so - in other words - he got something wrong, he did something he shouldn't have done," the popular host said.
"You think it's an agenda the BBC has got because we're covering the story, wise up!"
'Peter' accused Mr Nolan of being biased against the DUP.
"I just think everything the DUP do you have it on the show, no matter what it is, you obviously have it in for them," the caller said.
Mr Nolan reacted angrily to the claim and pointed to his record in covering scandals involving other political parties.
"You're not getting away with that comment mate, pop up to Sinn Fein's Senior Press Officer and ask him if we don't ever cover what Sinn Fein do. Ask him if he likes what we do on air and if he thinks we never cover Sinn Fein," he said.
"When you come off with this absolute nonsense, when you slip in wee comments I find that disgustingly offensive. I'm a journalist in this country and you're starting to talk like Trump, if a journalist actually covers a story we've got an agenda.
"Here's our agenda, to bring people like you the facts. It doesn't matter which political party it is, we will bring you the facts."
The caller had the last word with Mr Nolan before hanging up.