i am customizing some forms for Candidates and Contacts in Zoho

as i have been using zoho for the past 4 years, through another user, i found that even when advising candidates to enter the country code they simply ignore this, isn't there a way to control this ? it is a simple function which i found in many portals where you select your country and automatically it publishes the country code and give example to the candidate how to enter the rest of number and then it verifies it by the number of digits entered against that country digits business rule for phone or mobile, is there such a function here in zoho ?