The E3256 doesn't appear to function like a regular dongle. Up to this point, all the regular dongles I've used presents out what looks like a traditional modem to the operating system, and the Huawei client software is really just a wrapper which controls the OS dialler software. The OS still sends ATDT commands at the modem just like in the old dial up and USB ADSL modem days, it's all very comforting and retro
This is good for routers as they then have control over the 3g modem and it's the router that initiates the PPP session, which in turn means the router gets the IP address (this is the essential bit for the Claranet Mobility service which support static IP and routed ranges natively over 3G). The downside is the router has to have the right drivers to support the USB 3G modem, and with the speed these dongles change, that's an increasingly difficult challenge.
The E3256 works differently in that it presents to the OS an Ethernet port over USB rather than a modem. It then functions like a standalone router in dongle form, taking all the hard work away from the OS. Configuration is done via a web browser on a page which is served out by the dongle (just like a regular router). This is a great step forwards if you're using the dongle in a laptop, but is potentially bad news if you put the dongle in a router. Firstly it's the dongle that gets the IP address and then does NAT for whatever it's plugged into, so if the router could talk to the dongle you'd be NATing an already NATed service, which is a bit grotty.
I've not yet found out of the E3256 can be put back into a regular modem mode, which is what you'd really want to plug this dongle into a router. If not, there is a Huawei E372 which also supports DC-HSPA+ but I've no idea if that also works in the same way. I'm going to try and get in to Claranet a few different brands of dongle to see what works.
Hope this helps