It was a New York City phone number.
In the olden days after direct dial became the norm, telephone numbers (up into the '80s) had a two letter prefix where the first two letters corresponded with the first two numbers. On rotary phones each number had 3 letters, for example 2 was A, B, C, 3 was D, E, F and so on.
So PEnnsylvania was to help people (way back when) recall phone numbers. Each number prior to 1990 was seven digits. The area code existed but was ONLY used for long distance/toll calls. So this number with the PE prefix was 736-5000. (Before the 1950s there were only 6 digits, in this case the "6" would not have existed, it'd been 73-5000. As part of the adoption process of more residential phones coming online post-WW2, it was necessary to create more numbers by adding digits. Today, the area code overlays and shrinking geography of traditional area codes serve the same purpose: more demand for phone numbers.)
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