Problem to use default.pem certificate for 3cx softphone

Hi.
I’ve a 3cx softphone installed on my computer and i would to use it for tls conection
For this, I need a pem certificate and I tried to copy /etc/asterisk/keys/default.pem in to softphone, but not work
Someone has tried that?

Thanks

I imagine that is only meant to be used with 3CX