The “GSM chirp”. I never got to hear it much because my family happened to use CDMA phones in that era, but I do remember hearing it a few times. I know it was

The “GSM chirp”. I never got to hear it much because my family happened to use CDMA phones in that era, but I do remember hearing it a few times. I know it was well known. I haven’t thought about that in a long time.