Will the remote EC25-AF use the China Telecom 4G card to call and answer the phone in mainland China? Which part should the relevant AT instructions refer to?
You mean you want to use China Telecom 4G to test the EC25AF module in mainland China ?
As you know that EC25AF can support LTE B5, and China Telecom 4G also support B5, so you can use this card to test.
You just need to use ATD+phone number; to make a call, and ATA to answer a call. Thanks!