batch sending Whatsapp Message

Send message to large amount of whatsapp users (say 2k) Build a web user interface for admin to select a group of users, types the message and then send to their whatsapp account. The message need to support Tranditional Chinese The user info is maintained by uploading an excel file, with user name and mobile phone numbers. There is a report interface, showing which users have read the content and the time of read. Also showing which users have not read the content.