Most 3G/4G modems these days are USB connected and have QMI (for quectel chipsets) and / or MBIM both of which are easier to use from software than AT.
They still have a virtual comm port that talks AT though and that may still be required for a few diagnostic things.
Setting up a data connection over QMI / MBIM however is much easier and more efficient than messing around with AT + PPP
Setting up a data connection over QMI / MBIM however is much easier and more efficient than messing around with AT + PPP