Really? If I got an arbitrary call on my birthday from some business contact whom I hardly knew, I'd be wondering what was wrong with that person. Relationships aren't a bag of tricks.
It's not like he's calling to pitch anything. He legitimately wants to wish them a happy birthday and catch up with them. I guess some discretion is used when deciding to call someone. (He obviously had to know them well enough at some point to get their birthdate.)
I agree. A card in the mail would be more appropriate. A telephone call is something a bit too personal from someone with whom you've had no other contact in the prior year.
