How to trust a safety number of a contact

[heikone]

Hello,
I'm trying to trust a safety number of a contact, who changed his phone (so I guess the safety number of Signal was changed).

According to the documentation, I've tried by:
sudo -u signal-cli /opt/signal/bin/./signal-cli -a +49xxxx trust -v SAFETY_NUMBER 554137782304yyyyyy

But something seems to be wrong in my command.

Could anybody assist?

Best regards
Heiko

[heikone]

Managed it with help from FHEM Forum:

sudo service signal stop
sudo -u signal-cli /opt/signal/bin/signal-cli --config /var/lib/signal-cli -u +49<own number> trust -a +49<number to trust>
sudo service signal start

Gruß
Heiko