I have tried using the app a few times on my BT infinity router with full WiFi signal strength with always the same results.
The call goes through OK but the person I call always asks me to speak up as they can't hear me. When I speak as loudly as I can they report that at the end of every word I say there is a loud crack sound. I can also hear a crack sound at the end of every word they say which is just about bearable, but the person I called can't really continue the conversation because they can't hear me.
I can't complain about the app it's self as when I go to dial an 0845 number from my phone book, it clicks in and prompts me to use it, but in practice because of poor call quality it is unusable.
Is it just the HTC One XL on android has this issue or is it BT infinity lines?