Phone instead of GSM shield?

Question

Arduino

Hello.
Articles are circulating on the Internet on connecting old Siemens A / S / SL models to Arduino to send / receive sms,
and accordingly control end devices through these sms.
The problem is that these days it is not so easy to find these phones in good condition.
Which of today's cheap phones can fit this role?
To connect to the Arduino, and control the phone (for example, AT commands),
was as simple as possible.

Answer 1

All modern smartphones are connected via USB, so to get to it as a modem (to send an AT command), you need at least a USB HOST, which is not an easy task for arduino. It's easier to put the BT module and send via bluetooth through special software, then any smart will do.

Answer 2

almost any old phone works with rs232 look for connection diagrams to the phone.