I call that "Plug & Play"! Am really excited. ^^

With slight skepticism and after some search for a wireless router for a small apartment, in the just worth no fixed DSL connection but still would occasionally excellent wireless option is needed, I have this TP-Link router ordered. I had the Netgear 3G / 4G Router (also without UMTS modem) contemplated but then selected the TP-link.
I have experience with small, battery-operated, mobile wireless hotspots, and the size of a small cell phone, with an integrated SIM card slot. They're very good, but slightly absurd for the holiday because they really need there is no battery, on the other hand have relatively weak transmission power and also not the most sensitive receivers. But they also work well, and just like an upside mobile hotspot smartphone. Schick for spontaneous connection on the go, but not for a holiday.
Back to TP-Link TL-MR3220: The question was: which UMTS modem (pronounced Surfstick) take? Constantly changing models, compatibility lists and countless information on the Internet to make the decision lightly. All in all, the information I have decided for the Huawei E303 Stick, although this was not on the latest compatibility list.
Now the result: I have rarely had such a great plug and play experience, as with these two devices! A SIM card inserted without separate installations, just in the new drive, whether by EPlus (or blau.de or Aldi Talk) or Vodaphone (or Smart mobile Multisim second card) - this in the USB port of the new, never switched router stuck from TP-Link - turned this and stared at the blinking LEDs - clicked after 1 minute on the Windows 7 computer on networks - clicked the new network - on: not configured, new network: Configure now? clicked - clicked a few banal "Ok" and "next" sSchritte and entered the indicated on the back of the TP-Link Network Key - losgesurft!
Honestly I expected, first having to establish a firm connection with the supplied Ethernet cable and having to make dozens of settings, but it was really very simple.
(Was so tagesflat.eplus.de easily selectable) After that, I still under Advanced Settings changed the APN's, adapted to the network name (requires re-boot) and change other settings. Everything not a serious problem and quite self-explanatory to be found in the Settings menu.
The transmission power cuts across the great old building and the apartment is likely to penetrate with ease. So I see no reason for point deduction, and I hope that it stays that way :-)

Two comments:
1.) I used only SIM cards whose PIN registration lock was previously deactivated with a mobile phone (see Security settings). I think otherwise, there can be problems when logging in the mobile network because the software of the router it is not or does not support easily.
2.) The Settings Menu (which is called by the web browser of the connected computer) is completely in English. If you're that and it absolutely needs in German, this router should not buy. Although the printed Quick Start Guide is including in German, but that should not take much.