Buddy,
Most of the IT Companies \ MNC's do not verify employee's information on Call. If VO calls for verification, they will be asked to send an email with proper authorization.
Reasons
- No Matter what the other person may say that he or she is. True identity of the person calling can never be validated.
- Most of the times, Calls come from competitors \ Job consultancies checking on how much the other company is paying the employees. more of social engineering.
I once had the same questions that you have right now and that was my HR's response
She (HR) just informed that if VO really is interested in knowing \ verifying applicants and they are genuine sources of VO. Then they should not have a problem validating who they are by sending an email through VO official mailbox.
Note : Verification does not happen for everyone. It is totally based on the documentation provided and Visa Officer's discretion. In some cases, few cases are picked up for quality checks
Good Luck