Why doesn't the dialer recognize numbers as alphabetic contact names?

[New Daddy]

When I dial numbers, my XV6700 doesn't seem to recognize the numbers as the alphabets of a contact and display possible candidates from my contacts list.
For example, if I dial the numbers 5646, I expect my cell phone to show not only all phone numbers in my contact that start with 5646 but also names that match the alphabets under 5646 (e.g., "John").
Is this possible?