Although the FRITZ!Box is not CAT-iq certified, it supports many of the services and functions defined in CAT-iq. For example, the FRITZ! function "HD telephony" complies with the new standard and is therefore fully compatible with all CAT-iq-based products for HD telephony available on the market. CAT-iq 2.0-compatible cordless telephones from other manufacturers can also use convenience functions such as toggling calls, 3-party conference calls, CLIP/CNIP, and accessing the FRITZ!Box telephone book and call list.

The FRITZ!Box also supports CAT-iq SUOTA (Software Update Over The Air), which enables cordless telephones from other manufacturers to update the software of their telephones via the FRITZ!Box.

In addition, the FRITZ!Box and FRITZ!Fon models offer a multitude of other functions that cannot currently be implemented with the CAT-iq standard. For this reason, AVM does not currently consider it necessary to seek certification, nor are we planning to do so.