The iRig is cheap (ca €35), light and connects directly to your mobile phone. You can connect your microphone to the iRig using a standard XLR lead. Pop in a 9 volt battery, switch it on and put on a set of headphones. When the studio calls you can adjust the gain on the right hand side of the unit so that the level is clear. Works with all phones. One thing to look out for is that you can only hear the studio in your headphones so this can be offputting if you are interviewing someone in a loud area.
iRig sample recording - Download This Episode