When phone had been found at the first time. Phone just use to completing our voice communication need. Then, when newer technology was found. We know sms (short message service), as text communication service. Sms service has been caught pager user to use sms.
Then, not only for voice and text communication. Mobile phone in this day is also capable to use for communication data such as gprs for internet and 3G that capable to make video call and high internet speed access.