Number validation in Kannel!

[thejvmshid]

Dear support markjeee, many respected professionals, I will immediately say that this is not a problem! We need your professional advice in configuring Kannel. Namely, the validation of the number is of interest, for example: Suppose the valid number consists of 7 digits. Which option should be used so that the number of the sender or recipient is not more than and not less than 7 digits in order to eliminate random errors. I have an assumption that it's preferable to use the white-list-regex, but I do not think up the end :) For earlier thanks for the answer and again I apologize for writing in the wrong place.