Use Mail In Payment to enter client payment details that display on the invoice.
Merchant Partners is a credit card merchant gateway that is integrated with WHMCS.
The Merchant Warrior payment gateway module is available in WHMCS.
The Modulo Moip payment gateway module is available in WHMCS.
Moneris is a Canadian payment gateway.
Moneris Vault is a Canadian payment gateway.
The NaviGate payment gateway module is available in WHMCS.