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How do I ensure optimal operation of more than 25 devices in one location?

We will explain why it is that if you operate more than 25 phones and devices using the same IP address, a ban may be imposed and what you can do about it.

The cause

To guarantee the quality and reliability of all services, we have to protect our systems against malicious attacks. Accordingly, our infrastructure automatically detects such access and puts the IP address on a block list. All further requests from this particular address are then rejected without further verification.

This can also happen if a SIP client from your internal network makes incorrect registration attempts on our platform at high frequency. Since terminals with incorrect access data sometimes send new registration attempts very frequently, they can endanger the quality of the service for all participants. For this reason, we also block IP addresses that frequently send us incorrect registration attempts.

But even a lot of simultaneous successful registrations from one network resp. from the same IP address can lead to a ban. Unfortunately, there is no way to distinguish regular from malicious requests without endangering the security of our infrastructure, from which ultimately all customers benefit.


If possible, it can help to reduce the number of devices registered at the same time. For example, it makes sense to switch off unused terminals not only because of energy costs.

At the latest if you plan to register more than 25 devices simultaneously using the same IPv4 address, you should adapt your infrastructure to IPv6. The registration of the individual devices in the network will then no longer be carried out via the IP address of the router as before. Instead, each device is assigned its own unique address with which it registers with our system.

You should check the following beforehand:

  • Do my devices support IPv6?
  • Can my router manage IPv6 addresses?
  • Does my Internet provider offer IPv6?