Format of Employee Verification Form - how to begin the process - By calling or mailing the previous company?

I am an HR Professional working with an IT Education Industry based in Mumbai. We are planning to start verifying the credentials of new Joinees and for that I have to design an Employee Verification Form. Please guide me how can I start the process by calling or by mail the previous company of the employee.
I would be grateful to you if you coulf give me an all-inclusive sample of Employee Verification Form.

You should always seek a written employment verification of the employee from their previous HR Officers or Managers.
Please find a helpful link in this regard, below:
https://www.citehr.com/47350-re-empl...-download.html

Hi,
It would be courteous to call and speak to the HR of the previous employer and requet them that you would be emailing a Confidential Verification format, which they should fill and return by email.
During the conversation it would be prudent to check if there is anything averse against the employee being considered for employment, as most HR do not mention such things in the Verification format.