Fone ( Forensics )

Challenge: Fone ( contributed by yueming )

I used an online spectrum analyzer to check if there was a hidden word or image. However what i got was a bunch of bars with two lines in them. The name of the challenge was Fone and the audio sounded like a phone so I thought Dual tone multi frequency might be useful. I compared the higher and lower frequency for each bar and compared it to the DTMF table to get which key was being input.