Image copyright Chris Ferry Image caption The billboard was widely shared online, leading to even more congratulations

A New Jersey father has received thousands of birthday phone calls and texts after his sons put up a billboard inviting strangers to wish him well.

The sign, which greets motorists in Linwood, New Jersey, asks strangers to "wish my dad a happy birthday" and shows Chris Ferry's mobile number.

People from around the world have clogged his phone to help celebrate his 62nd birthday, he said.

Some have called to sing happy birthday while others share personal stories.

After the first sign went up on Thursday ahead of his birthday on 16 March, he received his first text from a man named Nick, he told a local Florida ABC News affiliate.

Mr Ferry then asked the stranger: "How do you know it's my birthday coming up?"

"I saw it on a billboard," the man said.

The sign is a practical joke set up by his two sons who live in Florida. The two men told KYW-News that they wanted it to be a "birthday for him to remember".

"We thought it was going to be a local joke, people would call," his son Chris said.

"I guess when we put it on social media, that's when it really started going crazy."

Mr Ferry said he has received tens of thousands of texts from around the world, including the Philippines, Kenya, Luxembourg, Ireland, Guatemala, Nepal and Australia.

Some people tell him stories of their own fathers, he said, or talk about other people they know that share a birthday with him.

"I can see my texts go from 10 or 20 to over 600 in a matter of minutes," he said, adding that he has not "been able to use my phone in a normal way".

According to his sons, the prank originated with their childhood trips to restaurants after hockey matches.

The boys, Michael and Chris, used to lie and tell waiters that it was their dad's birthday, and watch and laugh as he would squirm awkwardly as they brought him cake.

Mr Ferry, who strangers have been calling "the billboard dad", has changed his voicemail message to "thank you for calling to wish me a happy birthday, I really, very much appreciate it..."

After initially trying to respond to each message, Mr Ferry has given up and is looking forward to the sign coming down in April.

His sons said he is still laughing about it, and suggest that next year, they'll rent a larger billboard.

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