I haven't got an e3 yet, but since they've just come down in price I might get a pair. However, I do have a couple of the previous versions of the emailer which I just use as normal phones. I did have a bit of a look at the emailer to stop it having to dial up to premium rate numbers which annoyed me a bit.
What I did was configure the emailer to dial another modem instead of the premium rate number by using a cheap 4 port pbx. This, as someone else mentioned dials up and authenticates via CHAP. By prompting the emailer for authentication, I learned its username and password. You then see the amstrad try to connect to various servers and request configuration files over HTTP amongst other things. I configured my box to respond to all IP addresses and learnt what it was requesting. You could then use the above info to request the config files from the real server.
If you look in the retrieved gamma_a_live.config you see things like redial intervals, next advert collect time and stuff that you can alter to more reasonable values and feed to the emailer. I never registered the second emailer at all and it works fine.
Interestingly, the previous version had a config option: CameraSupport=0 so I presume the process is very similar, if not identical for the e3.
Paul