The iSendPro SMS is a professional bulk messaging solution for both text and voice SMS. The API supports the transmission of SMS to a single recipient or multiple recipients using mobile devices and fixed line telephones. Some of its functional features include: directory management, blacklist addition, text characters count, multi-contact campaigns, and detection of spamming numbers. A developer must sign up for iSendPro account to be able to access, integrate, and use the API to send SMSs to more than 200 countries. The RESTful API sends requests in HTTp format and returns responses in JSON and XML format.