how to validate phonenumber with out using localvariable?

In which variable you stored your data? It will be either local or RI variable.

What is this question about? Is there a specific reason to not use locals?

If you are capturing the value, then to store the value, you will need to have a variable. It can be either a Rule input or a local variable. 
If you are trying to validate an existing value, then you can do it without a variable.

Both ways have multiple ways of doing it. 

1. Regex Match
2. Specifying lower and upper bounds of the number (eg. 1111111-9999999)
3. Check the length of the value