Curious where a phone number is from? Here's an extension to my phone book post a few days ago. If a reverse lookup comes back with nothing you can still get some info.

Cell phone numbers aren't in phone books which makes reverse lookups impossible. You can still get two pieces of information 1) if the number is in fact a call phone number and 2) who the provider is. If the number is a land line, you can find out what town or city the number is in.

You get this information from the Central Office (CO) Code availability page. Each Central Office code covers 10,000 phone numbers and they are allocated in chunks that large. For example on the 613 page you can see that Bell Mobility has CO codes 858, 859, 921, 922 and others.

The allocation scheme also means is that a lot of numbers are unused (but at the same time allow for future growth). For example, the town of Pakenham and the surrounding area has all of code 624 and a lot less than 10,000 residents.

The last column on the availability table, Remarks, is interesting too. All of the Hull CO codes that have recently been changed to local calls in the 819 area code are now reserved in the 613 area code. There are numbers for special use (200, 311, 400, 411, 911, 939, 976) and even misdials -- check out 912, 914, 915 but not 913 (the 3 is far enough away from the 1 to reduce the chance of a misdial).