Clean up Incorrectly Formatted Phone Numbers using Excel

In our Utopian imaginations all the data would have been standardized and shareable across systems and people. But alas, the reality is totally different. We seldom get data in the format / way we desire it to be. In other words, the ingredients are all there, but for us to prepare the dinner, you must pre-process them.

Often this pre-processing or cleaning up the data takes quite an amount of time it self leaving very little to do the actual work. That is when you can use excel’s powerful data cleaning techniques to handle the situations.

One common problem with corporate data is incorrectly formatted phone numbers. Most of us are used to a standard 10 digit phone number format like 123-123-1234 or (123) 123 1234, but when you get that customer data, very few phone numbers in it are formatted like above. Instead you might see phone numbers like 1231231234, 12312 31234, (123)123-1234 etc.

It is not really difficult to clean up the phone numbers if we know before hand how they are formatted. For eg. you can easily convert a phone number like 1231231234 to 123-123-1234 using excel text formatting functions like =TEXT(1231231234,"000-000-0000"). But it is a rare case in which we have control over the incoming format and quickly you will have to use a slew of format / text processing functions to clean up the data.

To simplify the whole thing, I have written a small VBA UDF (User Defined Function) which you can add to your excel add-ins list and use to clean up virtually any phone number format to standard phone number.

Function cleanPhoneNumber(thisNumber As String) As String
    ' this function aspires to clean any phone number format
    ' to standard format (+9999) 999-999-9999 or 999-999-9999
    ' works with almost all phone number formats stored in text

Dim retNumber As String

For i = 1 To Len(thisNumber)
    If Asc(Mid(thisNumber, i, 1)) >= Asc("0") And Asc(Mid(thisNumber, i, 1)) <= Asc("9") Then
        retNumber = retNumber + Mid(thisNumber, i, 1)
    End If
Next
If Len(retNumber) > 10 Then
    ' format for country code as well
    cleanPhoneNumber = Format(retNumber, "(+#) 000-000-0000")
Else
    cleanPhoneNumber = Format(retNumber, "000-000-0000")
End If
End Function

The above function is pretty straight forward and simple. It scans the input text for any numeric ASCII codes and saves them to another text field. Once the scanning is complete the function will format the final number to 999-999-9999 format if the number has 10 or less digits, otherwise to (+9999) 999-999-9999 format (with country code).

Like this? Learn these other data cleaning / processing tips:

Handling spelling mistakes in your data
Splitting text using excel formulas
Generating initials from names using excel
Adding a range of cells using Concat()