VoIP traffic (SIP) passes through various ports within your network. External individuals can (deliberately) send data packets to these ports. This can cause your phone to ring with a strange number appearing on your display, such as 100, 101, or 1001. These calls are often immediately terminated as soon as you try to answer. This problem mainly occurs on Tiptel and Yealink phones. Some routers are also more susceptible than others.

These calls are essentially harmless. You won't find them in your call history in the partner environment, and you won't be charged for them.

To prevent this, you need to configure your firewall more securely. Our advice is to allow all SIP/VoIP traffic from our platform. The IP range you need to configure is described on the Firewall configuration page. You should block all other SIP/VoIP traffic. If you can't configure this on your router/firewall, you can also change the local SIP port on the device. By default, it's set to 5061 for extension 201. You can change this to 5091, for example.

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