Please change the following settings in your VoIP-client:
Port: 5060 (Alternative port: 5064)
user name: 00493012345678 (your telephone number in the international format)
Get your SIP password at the customer portal.
Please do not enter a STUN server. The mentioning of a proxy server is necessary in exceptional cases only.
Proxy: sip.easybell.de (use in exceptional cases only)
STUN server: (do not enter anything)