Weird voicemails with no call log, and call forwarding issues iphone 5

Tonight I have received several weird voicemails, some with just background noise and some with someone talking in a foreign language, all from mobiles. The most weird thing is that no calls have just come in, ie there's no missed calls. I tried ringing my phone from the landline and it does ring, and I can leave messages, and it logs a a missed call as normal. Anyone any idea why I'm getting these weird voicemails and why I'm getting no missed calls.

Also, a couple of weeks ago I changed my ring time by calling **61*901*11*25#, and since then everytime I turn the phone off and back on again, or do a soft reset the call forwarding icon appears at the top of the screen (even though I haven't set call forwarding up so it just rings through as normal). [ If I go into settings and go to call forwarding it's already set to off, and as soon as I enter this screen the icon disappears. Anyone any idea why this is happening?

P.S. I'd post some images of the icon but the insert image is not working :-/