Setting up call forwarding with o2

First: when should calls be forwarded?

Three kinds are available: immediately (your phone stops ringing altogether), when busy (the second caller does not get a busy tone) and on no answer (delayed — you get to pick up first). Most businesses combine delayed + when busy + when unreachable: everything stays as it was, only voicemail is replaced — by an AI phone assistant, for example. For an overview of every connection route, see "Setting up call forwarding: the four routes and their pitfalls".

Setting up forwarding with a key code

The codes are a network standard (GSM) and work on any handset, regardless of make:

1. Have the target number ready — the number calls are to be forwarded to.
2. Type the code into the phone app, like an ordinary phone number.
3. Press call. The network confirms the forwarding with a message on the display.

You can set the no-answer delay between 5 and 30 seconds in steps of 5. A practical value: 20–25 seconds — long enough to pick up yourself, short enough that callers do not hang up.

The alternative: the Mein o2 app or your phone's settings

If you would rather not deal with codes, call forwarding is available in two other places: in the telephony settings of iPhone and Android (the same network features sit behind them) and in the Mein o2 app. o2 describes the route in the Mein o2 app like this: "Menü" › "Tarif & SIM" › the "SIM & Vertrag" tab › "Anruf & Mailboxeinstellungen"; there you switch the forwarding you want from "Weiterleitung zur Mailbox" (to voicemail) to "Weiterleitung zur Rufnummer" (to a number) and enter the target number. According to o2 it can take a few minutes for the change to apply. These instructions come from an o2 guide dated 26 July 2023 — if the menus in your app are named differently, o2's help pages will point the way.

Prepaid or contract: a difference worth checking

This is a hard difference. On o2's current prepaid tariffs, call forwarding is possible to voicemail only (free of charge), according to o2's price list — you cannot forward a prepaid number to another number, such as an AI assistant's (Preisliste Mobilfunk Prepaid, as of July 2026). On contract tariffs, forwarding to other numbers is possible; what it costs is covered in the next section. Older tariffs may differ — the price list for your tariff is what counts.

Pitfalls: caller ID and cost

Caller ID (CLIP): if your provider's network does the forwarding (key code, app, customer portal), the standard has the destination receive the caller's number. Your own number typically arrives only when a FRITZ!Box or phone system forwards the call itself — and then an assistant cannot capture the caller's number automatically. Check it after setting up, with a call from a second phone.

Cost: the forwarded leg of the call is paid by the line owner, and o2 bills it separately according to its price list. On current contract tariffs such as O2 Mobile, O2 Free Unlimited and O2 Grow, forwarding to voicemail and within the o2 mobile network is free; to all other German mobile networks and to German landlines it costs €0.29 per minute or part thereof (Preisliste Mobilfunk Postpaid, as of 2026-07-08). If the forwarding destination is outside the o2 mobile network — a landline number, say — every forwarded minute costs extra. Do the sums once before you forward permanently.

The forgotten rule: a forwarding rule set months ago often only comes to light when calls start to "disappear". If in doubt, dial ##002# and set it up again. Note: on a mobile, voicemail is itself a forwarding on no answer. The new forwarding replaces it, and ##002# deletes it too — to get voicemail back, set its forwarding up again, in the Mein o2 app for instance via "Weiterleitung zur Mailbox".

What this means for your AI assistant

Nothing beyond this forwarding is needed — on an o2 contract; o2 Prepaid only forwards to the mailbox. Your scoco number is not an o2 mobile number, so on a contract the forwarded minutes cost extra, as described under "Cost" above. With scoco.ai you keep your o2 number, nothing changes on your phone system, and basic setup takes about 10 minutes. When a caller number is transmitted, the assistant offers to use it as the callback number — if the caller accepts, it is taken without being read back; with a CLIP problem, that is your own. A dictated number it reads back digit by digit. Hence the test call from a second phone. A planner in the dashboard shows the right codes, with your scoco number already filled in. Calls are not recorded; what you get are transcripts and summaries.