1. If you need a calling card to connect the computer in your dormitory to the Internet, then the calling card of Telecom may be more suitable for you, because the network coverage of Telecom is wider and the speed is relatively faster.
If you need a cheaper phone card, then Unicom's phone card may be more suitable for you, because Unicom's phone bill is relatively cheaper.
3. If you need a phone card with a more stable signal, then a mobile phone card may be more suitable for you, because the mobile network has a wider coverage and the signal is more stable.
So you can choose one calling card according to your own needs and preferences, or you can choose multiple calling cards according to your own needs.