1950's Cuba Trivia question?

I was watching "Our Man in Havana" which was filmed in Havana in the 1950's. In the film, there were signs with five digit numbers everywhere on the streets, lining street columns, on triangular hats worn by men, etc. At first I thought they might be street addresses, but they appear random and not sequential. There were no illustrations or text attached, so it does not appear to be telephone numbers or other advertisement. Just random numbers on individual signs. Does anyone know what they were?