Forms :: How To Disable Edits In General Tab But Not In Calls Tab

I have a form called Contacts that has two tabs. One is called General adn the other Calls.

In the General tab I have a bound field called CustomerIDdet which can be numeric or alphanumeric. I need to disable edits in the General tab but not in the Calls tab if CustomerIDdet is numeric (and it follows certain additional rules)

I have placed this code in the Onload even for the form:

Code:

If Len(CustomerIDdet) = 9 Then
If IsNumeric(CustomerIDdet) Then
If Right(CustomerIDdet, 4) = 9090 Then
If Left(CustomerIDdet, 1) = 0 Then
'disable editing in the General tab
End If
End If
End If
End If

I know how to disable edits control by control, but can I disable edits in all controls in that tab at once?