What business do many companies use to send text messages to customers?

This is called SMS group sending service, which is to use the group sending platform to send messages to protect your old customers and send some formal advertising information. The platform is free to use, and there is a charge for sending one, depending on how much you want.

At present, most companies send short messages to customers through short message platform, and the cost is generally around 3 cents to 6 cents. The receiver usually sees the mobile phone number and can't call back, but can only accept short messages.