Manage serial port from two processes simultaneosly

Question

I have the following scenario:

• Rasperry pi connected to a device via Serial port
• 3g Dongle connected to the raspberry (with the ability to make/recieve ca

Answer 1

Like all good GSM things there's a specification for that :)

GSM 07.10 is the specification and there are libraries out there for some time that can support you. Some are libraries you can build into your server systems and some are actual daemons.

A quick google for "gsm multiplexing" will get your started that I am sure.