Mobile broadband drivers on clean install

I've just bought a second-hand M4400 with mobile broadband.

I've added a boot SSD and done a clean install of W7 64 onto this.

I've sorted most of my drivers by downloading from the Dell website, but it can't seem to see the mobile broadband. I've tried the drivers for 5600 and 5620, and they both install ok, but the Dell mobile broadband app says something like "no devices found", and it doesn't appear in connection manager, or show a signal on the keyboard status light at all. I've inserted a mobile broadband SIM before installing the drivers.

How can I tell which mobile broadband card my M4400 has? And has anyone else had similar problems?

Next step if I get no joy here is to put the original hard drive in and boot from that to see if the shipped refurb-installation of Windows sees the broadband.
UPDATE: Just checked this - not showing on the shipped refurb-installation of Windows either.
Just to check - if it has a slot (behind battery) for a SIM card, that means it DOES have a mobile broadband card, yes? Dell don't just include the SIM slot even on models without the broadband card ??

Thanks.

 

Anyone?

If I have a SIM card slot behind the battery, does that mean I DO have mobile broadband?

They don't just put that slot in all M4400s, even those without the WWAN card?

 

Yes, every unit has the slot. Maybe check the bios if the WWAN shows up there.