It's best to test a 3G modem & subscription before making a long commitment,
If you intend to use it at the Radio end. Both for signal strength and suitability. In OH we have three networks (3G), of which one seems to work with RRC and the other one not (current status). The third one I haven't tested. The probable reason is somehow blocked incoming ports. As "P2P" traffic is usually forbidden in those subscriptions, operators might introduce restrictions later, or hopefully ease up things...
Best to test the firewall / port forwardings before starting to test 3G, if you have the possibility.
Regarding 3G modems it also helped me a lot to insert a few snap on ferrites on the USB lead between the router and modem. The downlink speed went up remarcably, and the modem seems to stay connected.
Joni