GXP2170 SSH command phone_status hangs and gives no reply



when I connect to a Grandstream GXP2170 remotely via SSH, I can send several commands to the phone.
“Help” shows which commands are possible at what level. One command is “phone_status”.
But instead of returning the status of the phone as it assumably should, it just hangs and does not return
anything… one has to manually interrupt the SSH-session via Ctrl-C…

What am I missing?

(The latest FW is applied)