What Ambiguous Numbers Are and Why They Are A Problem

Ambiguous numbers happen because

• An area code splits, and either
• the original area code splits again, or
• the new area code splits again,
• and you don't know the date of the original number -- or you don't know it accurately enough to know which splits apply to it.

An Example

If you put the phone number 205-296-1111 into PhoneSeal Desktop, it will report:

According to our records:
If phone number 205-296-1111 is older than 5/13/95, it has changed to 334-296-1111.
If phone number 334-296-1111 is older than 1/7/02, it has changed to 251-296-1111.
If phone number 205-296-1111 is older than 9/27/98, it has changed to 256-296-1111.

What is the current area code for this number? Is it 205, 334, 251, or 256?

You can't tell -- you have to pick up the phone and dial them all.

How Ambiguous Numbers Impact You

We estimate that it will cost you between $6 and $14 to manually correct a telephone number, by the time you add burdened overhead costs (management, rent, electricity, and so on, on top of the wage of the person doing the actual calling). This gets expensive fast! But in a database of 1,000,000 numbers, you could easily expect about 30,000 ambiguous numbers! That will cost $180,000 to $420,000!

It is also very slow. Very large files take months to correct.

How PhoneSeal Helps You Deal With Ambiguous Numbers

PhoneSeal Advanced and PhoneSeal Professional contain:

• Time Traveler -- our term for a set of features for advanced date handling. These features are:
  
  
  1. You can enter two dates: a starting and ending dates for putting upper and lower bounds on dates of phone numbers for your file or database
     
     
  2. You can use a data field in each record to specify an exact date or upper/lower bounds on the phone number(s) in the same record

Remember, the more accurately you can pin down the dates of your phone numbers, the fewer ambiguous numbers you will have.

• Zip Checker -- Zip Checker features are:
  
  
  1. You can use ZIP codes to assign area codes to your phone numbers when they are missing.
     
     
  2. You can use ZIP codes to resolve ambiguous numbers

Geographic Ambiguities

There is another kind of ambiguity, which is created when part of the exchange remains in the original area code, and part splits into another area code. Usually, all the number in the same exchange are assigned to either the current area code or the new area code. When the exchange itself is split, PhoneSeal can't tell, from the exchange code, what the new area code is.

For example:

• In 1999, exchange 612-681-XXXX split into 612-681-XXXX and 651-681-XXXX.
• In 2001, there was another split of the same exchange, when area code 651 was split into 651-681-XXXX and 952-681-XXXX.

So, knowing that the exchange code is 681 does not tell PhoneSeal whether the new area code is 612 or 651. Even knowing the exact date that the number was valid does not help.

PhoneSeal Advanced and Professional can use the ZIP code to determine the area code.

PhoneSeal Standard has no geographic data, so it reports these as ambiguous numbers. However, using ZipChecker, PhoneSeal Advanced and Professional can select the correct area code from the options available.