This is a great bit of kit that almost does what is on the box !!, it is simple to set-up and configure but its worth noting that you must change the country settings to make sure you get the right tones on the handsets.
There is one major problem with the hardware which is that when a PSTN line is plugged into the unit and through one of the config. screens you tell it not to ring the handsets when there is an inbound call on the PSTN line, does not work and the handsets still ring.
Gigasets technical support sounds like it is of-shore and therefore the agents, whilst helpful and responsive have zero hands on experience of the hardware and only go by screen-shots, which in this case are taken from a software version that is earlier than what the unit ships with and therefore useless.