Calling Without Cellular: How Wi-Fi Calls Work

June 23, 2025, 5:57 am | Read time: 3 minutes

Wi-Fi calls allow phone conversations over the Internet when mobile reception is poor. The technology uses VoIP, is automatically selected, and is free in many contract plans. However, some calls cannot be made using Wi-Fi calls.

Poor reception often makes phone calls a test of patience. But there’s a solution: Wi-Fi calls allow phone conversations over the internet when the mobile network fails. How do Wi-Fi calls work, and what requirements must be met? This article provides an overview of the technology and its usage possibilities.

What Are Wi-Fi Calls?

Wi-Fi calls are phone conversations conducted over the internet via VoIP (Voice over Internet Protocol) instead of the mobile network. This technology is already known from applications such as Skype, which was discontinued in May, and is also used by Deutsche Telekom for landline connections. With Wi-Fi calls, the phone automatically decides whether the call should go through the mobile network or Wi-Fi, depending on the current reception quality.

Requirements for Wi-Fi Calls

For calls to work over Wi-Fi, certain requirements must be met:

The phone must support Wi-Fi calls. Most current models have this technology.
The option must be enabled on the phone.
The phone must be connected to a Wi-Fi network.
An internet connection via DSL or cable must be available.
The plan must support Wi-Fi calls. Many contract plans offer this feature, as do some prepaid providers like Edeka Smart, Tchibo, Congstar, Ja! Mobil, Penny, and Aldi Talk.
For phones with an eSIM, the feature often needs to be activated by the provider.

Often Free, but Not Always!

Wi-Fi calls are free in current contract plans for private customers. In older plans, a monthly fee may apply for activation. Providers treat Wi-Fi calls like mobile calls and bill them accordingly. With flat rates, the calls are free; with plans that have free minutes, the time spent on calls is deducted from the allowance.

Special caution is advised for international calls:

For calls from Germany to abroad, the contractual costs for international calls apply.
For calls from abroad to Germany, the call is billed at domestic rates and is free for flat-rate users.
Calls from abroad to abroad can be expensive, as the costs for an international call from Germany to the foreign network are charged.
Incoming Wi-Fi calls are free, except for collect calls, where the recipient bears the costs.

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Activating and Deactivating Wi-Fi Calls

Apple iPhone

Activating and deactivating Wi-Fi calls on the iPhone is simple:

Open Settings.
Select Cellular.
Tap on Wi-Fi Calling.
Toggle the switch for “Wi-Fi Calling on This iPhone.”

If the Wi-Fi Calling option is not visible under Cellular, you may find it under Phone in Settings.

Android Smartphones

For Android smartphones, the process varies by manufacturer. Usually, activation is done through the phone app:

Open the phone app (receiver icon).
Tap the three dots in the top right corner.
Select Settings.
Toggle the switch for “Wi-Fi Calling.”

This article is a machine translation of the original German version of TECHBOOK and has been reviewed for accuracy and quality by a native speaker. For feedback, please contact us at info@techbook.de.