To use this app you have to take multiple steps including calling your carrier and turning off your voicemail. Then you "call" a long number that is supposed to start the app. That never worked. I called "you mail" for help, but because I am not a paying customer they never got back to me. Multiple calls to my phone carrier, lots of time on hold, tons of frustration and several perplexed friends because I had no voicemail-and I am deleting this POS.
Jamesjdk about YouMail: Block Spam on iPhone, v4.1.16