Setting up call forwarding on the FRITZ!Box

When the FRITZ!Box is the right place for forwarding

In many small offices the FRITZ!Box is the telephone exchange anyway: the landline numbers hang off it, often several of them. That is exactly where it plays to its strength — rules per number. You forward the office number to the assistant with a delay, the private number not at all, and the fax number stays untouched. A GSM code on a mobile cannot do that; some providers' customer portals can also forward per number, but the FRITZ!Box adds schedules and special cases. An overview of all four connection routes is in "Setting up call forwarding: the four routes and their pitfalls".

Step by step: creating a forwarding rule

The menu labels are as given in the FRITZ! knowledge base (current FRITZ!OS, as of 2026-11-02); the English labels are those of the English user interface. In older FRITZ!OS versions labels can differ slightly:

1. Open the user interface: go to fritz.box in your browser and log in with the device password.
2. Go to call diversion: "Telephony" → "Call Handling" → the "Call Diversion" tab.
3. Create a new forwarding rule: click "New Call Diversion", enable "Calls to" under the calls to be diverted, and choose the number the rule should apply to.
4. Set the forwarding type: the "Type of Diversion" list includes "Immediately", "delayed", "when busy" and "parallel call". For replacing voicemail, "delayed" is the standard case — you get to pick up first.
5. Enter the target number: choose the "To destination phone number" option, enter the number — that of your AI phone assistant, for example — and save with "Apply".
6. Test it: call the forwarded number from a mobile and let it ring. If the call arrives at the target, the rule is working.

Time control: forwarding only outside office hours

The FRITZ!Box's telephony functions can also control call rules by time — for example so that calls in the evening and at the weekend are handled differently from calls during office hours. To do so, under "Telephony" → "Call Handling" → "Call Diversion" you enable "Switch call diversion on and off by schedule", mark the times in the weekly overview when forwarding should be active, tick the forwarding rules the schedule should apply to, and save with "Apply". The schedule first takes effect at the next switching time. For replacing voicemail it is often not needed at all: a delayed forwarding rule does not get in the way during the day — it only takes effect when nobody picks up.

The limit: the rule only lives while the box is running

This is the honest difference from network-side forwarding: a FRITZ!Box rule is executed by your device. If the power fails, the internet stutters or the box happens to be restarting, the forwarding does not take effect either — calls then go nowhere. The FRITZ! knowledge base names one exception: if the box is left to choose the number used for diversion automatically, it tries to set up immediate, delayed and when-busy forwarding at the provider's exchange — they should then work even with the box switched off. The box does not show whether that succeeded, though, so do not rely on it. Network-side forwarding stored at your provider, by contrast, works independently of your hardware. Rule of thumb: Differentiated rules → FRITZ!Box. Maximum resilience → network-side at the provider. Anyone combining the two should document exactly which rule sits where.

Further pitfalls

• Cost: the forwarded leg of the call is paid by the line owner, depending on tariff and target number — that is how 1&1, for example, puts it for its landline connections (as of 2026-11-02). Whether your flat rate covers it is in your provider's tariff and price list — worth checking once.
• Caller ID: if the box carries out the forwarding itself, it sets up a second call to the target. Whether the caller's number or your own arrives there depends on whether your provider lets the caller's number through — more on that in "Why the AI sometimes sees the wrong number (the CLIP problem)". Make the test call and check which number arrives. An assistant reading a dictated callback number back protects against mishearing — not against a wrongly transmitted number.
• Old rules: forgotten forwarding rules from earlier experiments are a classic. Look through the existing list once before setting a new one up.

What this means for your AI assistant

Whether by FRITZ!Box rule or network-side: one forwarding rule is all it takes. With scoco.ai you keep your number, nothing changes about the rest of your telephony, and basic setup takes about 10 minutes. When a rule in the phone system is worth it, and when it is not, is covered in "Do I need to change my phone system? No — and when you do".