Where is area code 01415?

There are two possibilities for that number.

1. It is a domestic telephone area code in your country. However, there are several countries in which 01415 or similar could be a valid domestic area code, and you didn't say which country you're asking about. For example, in the UK, 0141 is the area code for Glasgow, Scotland.

2. You left off a zero from the front and are asking about an international number. Here again it gets ambiguous, because the answer depends on what portion of the number is your international access prefix (dependent on where you are calling from) and what portion is the actual telephone country code and area code. 00 1 415 is the way many places dial +1 415, which is the area code for San Francisco, California, USA. However, 001 41 5 is the way some places would dial a number in Switzerland (country code +41), and 0014 1 5 is the way some other places might dial a number in North America (country code +1). Because of the potential for confusion, it is best to write an international telephone number in correct international format, beginning with the plus symbol and the correct telephone country code.