Where in Pakistan is telephone area code 0431?

Answer 1

Pakistan's area code 042 (or +92 42 in international format) is Lahore, and local numbers generally begin with 3.

Answer 2

Pakistan's telephone area code 0431 (international: +92 431) is Gujranwala, Punjab.

(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)