SMS is “Short Messaging Service”. Ideally, messages will be 144 characters, and the message is sent unencrypted using the voice service of the carrier. This means any cellular phone with voice services will also have SMS. People who would write more than 144 characters will usually have their message split up, sent through the network, and the put together by the receiving phone. This is especially true for smartphones. The advantage of SMS is everyone has it. This is truly device agnostic as it can be used on smartphones, KaiOS phones, and even basic cellular phones.