I just installed Uplink yesterday but am having consistently choppy sound on the incoming sound. According to the people at the other end, it sounds fine to them. I see a couple of posts regarding this, but no replies.
In my case, it's a Trixbox install.
I've got a VTech portable Skype phone running off the same system where the Uplink and Skype are installed. Sound quality is fine there.
The Asterisk is a Trixbox 2.2 installation, no zaptel devices (ie, for timing).
I've only configured it for outgoing calls at this point. My other trunk on the system runs flawlessly.