Is it only smart phones that can send text messages while listening to music on the Internet?

Well, only smart phones can run in the background, just like computers can run multiple softwares at the same time without affecting each other.

For example, take Nokia's smartphone as an example. You can hang up Q, surf the Internet with UC browser, play games, make phone calls and send text messages at the same time. But it is impossible for non-intelligent machines. For example, if you hang up Q, you can't make a call until the Q software is started. To put it bluntly, you can't operate two things at the same time. Understand?

I hope it will help you and I hope it will be adopted.