Against all odds, Mayor Bloomberg fielded a 311 call yesterday, and the person at the other end was a Merrill Lynch employee who worked with him 30 years ago.

The mayor seemed as dumbfounded as the caller, who made the “ceremonial” 100 millionth call since the service was introduced in March 2003.

“I can’t believe it,” said Bloomberg. “Merrill Lynch. That’s unbelievable.”

Not only did he get to chat with the mayor, but the caller also got an answer to a question about when the garbage in his neighborhood was being collected.