Tianyi is the brand of China Telecom.
A service package of Tianyi can include ADSL broadband, CDMA mobile phone service, wifi access and other services.
Actually, it's not responsible at all. The original CDMA card can not be used on other mobile phones, but only on CDMA mobile phones. You have to ask why ITU (which sets communication standards) supports Qualcomm (the founder of CDMA) in this way.
The state allocates CDMA to telecommunications for anti-monopoly. So telecommunications can only use CDMA, which is incompatible with other operators.
Tianyi is just a brand of telecom, including all kinds of telecom services.
As long as it is a CDMA mobile phone (which will also be packaged as Tianyi mobile phone), you can use a CDMA card. Unicom doesn't have CDMA, it's all allocated to telecommunications. Telecom mobile phones and PHS have been cancelled. So now all telecom mobile phones are CDMA.
Is that clear? Ha ha. What is difficult is not consumers, but the complicated telecom technology, rights and monopoly in this world.