MsgClub WHMCS SMS plugin enables you to send SMS messages automatically to your all clients mobile numbers on certain activities like client login, message for new invoice, overdue invoice, password change etc. Our bulk sms addon also allows business owners to provide two-factor authentication to their customers and admins upon login and before accessing the client area where they need to enter the verification code sent on mobile number. because you are now enabled to remind your all clients on a defined action. So, they will love to take services from you.