The phone can't answer the phone, and the call settings prompt "Connection problem or invalid MMI code". What is the reason?

Check "Call Waiting" in Settings-Call Settings-Voice Phone-Other Settings.

First, call the operator to confirm whether the service has been opened!

Please confirm that your mobile phone is an ordinary Internet phone with IEM code. Press *#06# to appear. Support call forwarding settings.

When setting up a dual-card mobile phone, it should be noted that the IEM code should correspond to the mobile phone card to be successful. Don't confuse the two cards!

If the call forwarding service is turned on, please try turning off the phone and restarting it!

Restart. no We will call the operator and tell them that this function has been turned off.

Then keep the phone turned on and call the operator to reopen it.

Shut down and restart, and you can basically set up a successful call transfer!