No register snom 715

Hello dear community, I have a snom 715 at home and I try to configure it, but after rebooting the phone I get the message "Not registered". I guess I have the wrong configuration, do any of you have a manual that I can use to give the correct values?
I guess my mistake is in the account parameter, I'm not sure what is the correct value.
Also the phone restarts automatically from time to time.

Thanks in advance for your help.

Best regards!

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