It's impossible to know what this circuit does just by looking at the scematic. The chip on the left is an atmel microcontroller, its functioning is completely dependent on it's programming.
The MAX2622 is a voltage controlled oscillator. perhaps the µC generates a certain voltage using pwm and plays a tune this way? just a guess
The letters "GSM" indicate to me it might interface with a phone. I'd guess its some kind of frequency generator - maybe even a mobile phone jammer, but i have no idea.