Hi,
I'm brand new to the Arduino scene so please be kind. I am looking into building a water sensor project like the one here on Instructables.com http://www.instructables.com/id/Sump-Pump-Alarm/ . In this instructable it is using an arduino uno rev 3 and a sim900 gsm/gprs shield. But I already have a GSM Cellular dialer that I want to use since I already have it. How would I connect the arduino uno to my GSM Cellular dialer? The dialer accepts a standard RJ11, so can I just connect 2 of the RJ11 pins (Rx & Tx) to the arduino board? Thank you in advance for any help. The Arduino looks like it might be lots of fun.
Welcome in Arduino land,
If the GSM cellular uses 5V levels you should be able to do that.
If the GSM uses higher/lower voltages you need to add a voltage converter in between.
Thank you for your reply. I'll report back what I find