Why doesn't SMS need data?

Sending text messages will not generate traffic. Short messages inserted into pictures or too long short messages will be replaced by MMS.

Sending MMS will generate traffic, and MMS is received or sent through GPRS network.

MMS mobile phones receive or send traffic, which is free of charge and will not be included in the traffic package or monthly rent.

The network sends SMS or MMS through the network, which will generate traffic, which is included in the traffic package or monthly rent.