Is it safe to use virtual mobile numbers for account verification & authentication for services such as PayPal, Twitter, Gmail, Linkekdin, etc.? And what is the security drawback for this?
The question is whether its a one time use and forget, or is it kept in their database and used for future verification
If you are certainly sure that it is a one time usage, I don't think there is any problem using a virtual number.
If not, you might end up losing control of the account if you are required for that number (two factor auth for example) or in a very rare case someone else who currently has that virtual number can gain control over your account (more science fiction than reality)
its getting tough to use the online numbers for verification. Last time I try with one application, but they are using missed call mobile verification ( some thing like Cognalys) and the virtual numbers are not showing any call logs. The last five digits from the missed call number was the OTP... :)