Blimey, I can't remember where I read about it now.
Certainly the spec seems to indicate it's just a 56K type analogue dial-up modem, but something is nagging away in my brain. Probably just rats!
RJ11 is the plug format used for dsl/analogue/phone cable connection, whereas RJ45 is the similar looking but differently proportioned plug used for Ethernet cabling, and they are not the same at all.
I suspect that you just need a modem cable instead of a standard phone cable, if that's what your using.
I'm a bit rusty on this, can anybody else remember if the dsl/analogue modem/phone cables are all different internal wiring?
Can you hear it tone-dialing on another phone handset?