[0ptima]

I was hoping of something more along the line of
^[0-9]{7,8}$

Here is the blurb for VB's help ...

Regular Expression (Select, Input, Radio, Textarea only)
You may require this field's contents to match a PCRE-type regular expression. For example, you could have a field that is for the user's ICQ number. Since ICQ numbers consist of only numerals, you could write a regular expression to check for non-numerals.

Example: (Do not start or end the expression with an escape character)

^[0-9]{7,8}$

If you want to allow an empty response to be given, you need to account for it within the regex:

^[0-9]{7,8}$|^$