I'm actually finding it quite practical. I have Sprint as well and I'm aware that poor SNR will cause the audio to cut out. But, my goal was to improve my mobile (in car) operating experience and these weak signals would not be heard at all in a mobile setup due to engine noise. Also, it would be impossible to contact a weak station due to the low ERP of the mobile antenna - especially on 75/160 meters. Though it isn't the same as operating at the desk, it works way better than my previous mobile operation and I don't have to deal with a big-ass screwdriver antenna.
I designed this for myself but will make a few for those interested. The design is implemented on a small PWB and the software is getting better and better. If remoteshack was around a few years ago, I would have done that and saved myself the work. However, I think my design has the advantage of caller ID selectivity, which makes it easy to share the line and simplify connecting.
I just sold my remoteshack. Doing remote by cell phone is not practical in most cases. I use sprint here in Dallas, Tx. When I first got my remoteshack it worked great with my android phone. Then Sprint decided to use some DSP processing in their system. It see the noise on HF as something it needs to get rid of. After a few seconds on the HF bands all audio is gone because of this. Weak stations cannot be heard. I could hit a DTMF tone and get a few seconda of audio back.
I spoke with John who developed the system and this seems to be a common problem he runs into.
The system did work well from a landline. Another option was skype but the voip over a cell phone connection is not the best.
I would consider this before you spend too much time developing something.