SMS (short message service) is the text messaging service component of most telephone, Internet, and mobile device systems. Since it is used by most hearing people, it gives deaf people direct abd independent access to long distance communication with both hearing and deaf people.
The first test SMS message was sent in 1992.
WhatsApp, is an American freeware, cross-platform messaging and Voice over IP (VoIP) service owned by Facebook, Inc. It allows users to send text messages and voice messages, make voice and video calls, and share images, documents, user locations, and other media.https://en.wikipedia.org/wiki/Text_messaging