Have I just been phone spammed?

Odd thing just happened. I got a missed call on my mobile from a number I didn't recognise (07090 203810). The prefix 07090 is used for personal numbering. Its odd because I get a solid 5 bar signal at the office so the only way I could miss the call is if they rung and hung up before my ring tone kicked in. I called back and got re-directed to a recording of background music. I hung up quick because I have no idea how much the call was costing. I'm wondering if this comes up in the list of scams along with texting people a "You've won, text back to claim prize" variety. If only the Ofcom site wasn't so crap. So can I be arsed taking this up with my mobile provider? I guess its what scammers rely on.