Is there a router I can connect a USB 3G modem to?
Does anybody make a modem/router (gateway) with a USB connection so that I don't have to use an ADSL (telephone line) for broadband?
In other words, can I connect a mobile 3G dongle and still have my home network?
3G router for USB modem
check out the new Dovado UMR. You can connect most of the USB modems on the marked today.
And another three options for you...
Sarian (http://www.sarian.co.uk) do some nice routers, in various combinations of wired (ISDN, xDSL, etc) and GPRS/3G/HSDPA. They're mainly aimed at remote point-of-sale and telemetry apps. One really nice feature is that most can support 2 SIMs so can failover to a second network if the first one goes down. They've just been bought by Digi, so it'll be interesting to see how things pan out on that.
A bit more expensively, Cisco have just launched a SOHO router (the 880 series IIRC) and one of those supports GPRS/3G. Otherwise Cisco can sell you an 1800 series router with a 3G interface card (£££).
Alternatively, Checkpoint's UTM-1 Edge firewall/router box can take a USB dongle and use that as a backup link.
HTH, and good luck.
Router that takes 3G SIM card
Here's something similar The Ericsson Fixed Wireless Terminal W25 takes a sim card and does most of the usual things, Also supports HSDPA @ 7.2Mb/s
The sonicwall device only accepts PCMCIA cards. The best solutions seem to be from CradlePoint (linked from first post or go to http://www.cradlepointsolutions.com/shopDetails.asp?CatId=13&SubCatId=9&ProductId=49)
Not for the faint-hearted but certainly a budget option:
Take an ASUS wireless router, most of which come with one or more USB ports. Replace the firmware with open-source OpenWRT (www.openwrt.org).
Connect a Nokia mobile phone with the USB cable provided to the ASUS (I used an old 6680, but new-fangled HSDPA models like N95 should work as well and they give you more oomph). The Nokia acts as the modem and can be controlled with the venerable AT command set.
Install and configure ACM driver and PPP on OpenWRT. This is the hard bit and requires a fair deal of patience/smokes/coffee/wine and not to forget, Linux admin skills. Guidance and help is available on the OpenWRT forums.