FreePBX and OpenStage Phones


I’m a newby with FreePBX and I try to get 2 OpenStage Phones (one 40 and one 60) work.
I run FreepBX on a raspberrypi.
Both Phones are registered on the server and shown as online. On the phone itself all error messages disappeard and when I pick up the phone I can hear the free sign.

I configured 2 extensions in asterisk one ist 1001 and the second 1002 - these are also the terminal numbers on the phones.
When I try to call the other phone nothing seems to happen, but the CPU goes directly to 100% and falls to 0% by hangin up.

I tried to tail the logfiles but did not see anything that makes sense to me.

Can anyone please help me?

br Stefan