What is going on?
VoIP traffic (SIP) uses various ports within your network. External parties can also (intentionally) send data packets to these ports. This can cause your device to ring with a strange number displayed, such as 100, 101, or 1001. These calls are often disconnected immediately when you try to answer. This problem mainly occurs on Tiptel and Yealink devices.
These calls cannot do any harm in principle. You will also not find them in your conversation list in freedom.voys.co.za and no conversation costs will be charged.
First, check if your device is connected to a modem or router with an active routing function. You can do this by finding out the IP address of your device. If the IP address starts with 192.168.xxx.xxx, 172.16-31.xxx.xxx, and 10.xxx.xxx.xxx, then your device is properly connected.
To prevent the calls, you need to better secure your firewall. You can find more information in this guide. If you cannot set this up on your router/firewall, you can also change the local SIP port on the device. By default, this is set to 5060 for device 201. You can change this to, for example, 5090.