When did phone numbers become 7 characters? (not including the area code.)?

I just got a 2 gallon ceramic jug marked "Frank D'Angelo %26amp; Sons Liquor, 128 Union Street, Brooklyn, phone Hamilton 1192". I can't seem to find out anything about the store, when it was in business, etc. Does anyone have any info or ideas? I've tried everything I can think of to look it up and I'm getting no where. I did find a Frank's Department Store which used to be at thast location for 70 years. But, I think it's unlikely that a Dept store bottled or sold liquor.When did phone numbers become 7 characters? (not including the area code.)?
Going from 6 to seven digits occurred in the late 1940s I think.



The number on the jug, HAmilton 1192 meant that the HA were the first two numbers in the phone number, hence the reason we started having letters associated with the numbers all the way back to rotary dial phones. It was thought that remembering a word or name at the beginning was easier than 6 numbers. When numbers ran short, they added another after the letters.... like NEwmark 2-3968. Area codes were introduced in 1951. 6 and 7 digit numbers were mixed together until the late 1950s in some places. Sometime in the 1960s the letters were dropped altogether by convention. Before area codes, you had to have an operator get a long distance exchange to call out of your area.



The fact that there was a Frank's Dept store and it says Frank D'angelo %26amp; Sons seems like more than coincidence to me. Try to find out if Frank's Dept. store was owned by a guy named D'Angelo and case solved. It's not entirely impossible that the department store had it's own line, or maybe a liquor department in the store and they stamped the bottles.When did phone numbers become 7 characters? (not including the area code.)?
Phone numbers have been 7 digit for many years. You no doubt that the various numbers have corresponding letters. The phone number indicated on your jug was probably HAM 1192. Now it would be the numbers for the letters HAM.

Hope you get some information on your jug and the store.