An Arduino, an Adafruit Wave Shield, and a small speaker make up the balloons’ brain. The team used the waverp library to record and play back sounds through their shield. 3 lithium coin cells ...

The Arduino periodically rings the phone, waiting for someone to answer. Once the phone is off the hook, the Arduino uses a Wave shield to start playing back the scripted audio files.

The Wave Shield requires assembly and there is a lot of soldering, so do that first. When it’s all together it will plug in nicely on top of your Arduino board.

Arduino devices have had the option of a GSM linkup for awhile, but getting that cellular link to truly strut its stuff hasn't always been easy, even for those of us who'd be inclined to program ...