The issue is linked to DATA, ie 3g or Edge. Disable these options and you will be able to use your phone as a phone!!

As soon as you enable data then you will see that your phone drops calls and reception like crazy.

Apple can fix this with an OS update, they have been made aware.

The antenna was poorly created, good idea, bad design.

To use your phone without any line/signal drop, goto:

Settings/general/network/disable Cellular Data and disable 3g.

Also notice once on Wi-Fi you should not experience any signal drop no matter how you hold the phone.

New FW should be out next week or so, so this is just a temp measure to get rid of the annoying signal issues.