Since 15 July EU telecoms providers have not been allowed to charge for using a phone abroad within the EU, subject to a fair use policy. However, O2 Deutschland will not give customers free roaming unless they first send a text to the company asking to switch to a new tariff.
This is in breach of both EU regulation and the German Act Against Unfair Competition, VZBV said.
"In VZBV’s view, EU roaming rules apply automatically without consumers having to submit a request to their mobile phone provider. We believe that public statements made by the European Commission back us up in this respect," says Heiko Dünkel, legal officer at the consumer body.
"Having issued a formal warning to no avail, VZBV will now initiate court proceedings against O2," he said.
The EU has defined how much mobile operators can now charge one another when customers use their phones abroad.
Wholesale price caps will now be €0.032 per voice call, and €0.01 per text message. Data charges will gradually reduce, from €7.70 per gigabyte on 15 June to €2.50 by the start of 2022.
Lower caps for data transfers will allow EU consumers to access more data such as audio-visual content when travelling.