Enhanced Messaging Service (EMS) was a cross-industry collaboration between magic4, Ericsson, Motorola, Siemens and Alcatel among others, which provided an application-level extension to Short Message Service (SMS) for cellular phones available on GSM, TDMA and CDMA networks.
EMS is defined in 3GPP Technical Specification 3GPP TS 23.040 (originally GSM 03.40).
EMS was a technology designed to work with existing networks, but was ultimately made obsolete by MMS.
An EMS-enabled mobile phone could send and receive messages that had special text formatting (such as bold or italic), animations, pictures, icons, sound effects and special ringtones.
EMS never really picked up due to interoperability limitations and in fact very few operators ever introduced it.