As an example, for China you can send text messages using MED with the following mobile operators:

China Mobile
China Telecommunications Corporation
China Unicom

in Brasil we support:

14 Brasil Telecom Celular S.A (Brasil Telecom Celular Now TNL Oi)
Amazonia Celular S/A (Amazonia Celular Now TNL Oi)
CLARO S.A (Claro)
CTBC Cellular S.A (CTBC Cellular)
Nextel Services De Telecommunication LTD (Nextel)
Sercomtel Celular S/A (Sercomtel)
TIM Celular S.A. (TIM BRASIL)
TNL PCS S.A. (TNL Oi)
Telemig Celular S/A (Telemig Now Vivo)
Vivo S.A. (Vivo)