This has helped make it a popular alternative to SMS and MMS message services.

BBC: Whatsapp

It can send a message to all message addresses (phone number, e-mail address, instant messaging screen name) for all message types (voicemail, e-mail, instant message, SMS, MMS, fax).

FORBES: Magazine Article

The Stop Texting Fair Use Act, or STFU Act, would apply to message transmitted using the Short Message Service (SMS) as well as messages containing image, video, and sound content (MMS messages).

FORBES: As Deficit Soars, Congress Suggests New Tax On Text Messages