SMC7004AWBR - 802.11b router and 4port switch. I think that is the model, it has been Discontinued, has a serial port built in (use external modem to connect) and can use for dialup primary or backup to a wan connection. You need a dialup ISP w/ a PPP connection, can't use an ISP that requires a program to connect--as you can't run the program ON the device.
Alternatively can use a Dlink 704 or SMC 7004 (also discontinued)... basically same thing without the wireless component. It has a serial connection but no wireless access point. You can add a standalone WAP to the lan side and go that route. I have that exact solution. I used it for a wireless to dialup router and it works fine with only one pc connected via the WAP.
Since both products have been discontinued you can search ebay and probably get one for cheap. There are still occasional firmware upgrades for these models as they have support in Taiwan from a few vendors who have repackaged the hardware in different cases. 1.96 is the latest version and has SNMP support, uPnP, etc.