Joke Collection Website - Public benefit messages - What does it mean to support the voice and SMS functions of China Mobile or China Unicom's 2G segment?

What does it mean to support the voice and SMS functions of China Mobile or China Unicom's 2G segment?

It is voice and short message that can only be used under GSM network standard.

At present, the network standards of the three major mobile operators are 2G and 3G. Mobile: TD-SCDMA+GSM, Unicom: WCDMA+GSM, Telecom: EVDO+CDMA.