This might be off topic, but AFAIR there are PPP type PDP contexts where not raw IP, but actual PPP frames are transmitted over GPRS inside SNDCP/LLC. Not sure if any operators use that, but its perfectly valid.

In this case PPP doesn't terminate in the modem, so "hardware" support should be irrelevant.

Regards,
Harald
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Sent from a mobile device. Please excuse my brevity.