modem is not a problem, in emulator code it was implemented since past decade I think.
but you and others expecting "you can click and it will be online", which means "other side" i.e. internet service provider dialup server have to be emulated as well, with all that PPP/SLIP, DHCP, NAT etc network stuff. and it is not emulated, mainly because here is/was no "network guys" in dev. team.