Failed call "Phone is Busy"

Since successfully getting AltEPG working on 30 May, I've disconnected the dialup line most of the time to avoid the Ring Back problem. I've had about 3 successful Daily calls since 30 May - last on Fri 10 June, but I usually get "Failed. Phone is busy" and occasionally get "Failed to connect". Can someone clarify the meaning of these?
In particular, does "Failed. Phone is busy" mean TiVo thought *my* phone line was busy (it wasn't) or the AltEPG modem was busy?
Update: Just now - when I tried to add a dozen pauses to the prefix to stop the Ring Back, I got "Failed. Number not answering".
In particular, does "Failed. Phone is busy" mean TiVo thought *my* phone line was busy (it wasn't) or the AltEPG modem was busy?
Update: Just now - when I tried to add a dozen pauses to the prefix to stop the Ring Back, I got "Failed. Number not answering".