Contacting and acting on a client
A client screen has call, text and email buttons at the top and a WHMCS button that opens their full record in the admin area. The first three are device links: they hand off to the phone's dialer, messages app or mail client, so they work with no signal and change nothing. Call and text appear only when a number is on file. Below the balance sit record actions: add credit, email their overdue invoices a reminder, and close or reactivate the account. Close sets the account inactive so they cannot log in; it is reversible by reactivating, which is why it is offered where deleting a client, which erases everything they have, is not. As everywhere else, which actions show is decided on the server from the account's state, and each runs the documented WHMCS API call.