Deutsche Telekom is pressing for Europe-wide rules to stop the misuse of prepaid mobile phone accounts by terrorists, including those who carried out attacks in Paris and Brussels, according to Bloomberg. The carrier will reach out to politicians, competitors and regulators to discuss possible measures including mandatory ID checks for people who buy prepaid cards and a limit on how many each person can buy, according to a spokesman, Andreas Middel.

Tightening the rules could make it harder for terrorists and criminals to use mobile phones in their activities, taking away a tool used to obscure their identity and elude wiretapping. Prepaid cards are loosely regulated, and some European countries don’t require buyers to present identification or register. The cards can be moved freely within the European Union. “If there is to be new regulation to stop the misuse of prepaid cards then it should apply all over Europe,” Middel said by phone. “The problem is that right now, there are very different rules in Europe that in many cases leave room for misuse.”

Deutsche Telekom’s Hungarian unit, Magyar Telekom, alerted local authorities last year about the misuse of prepaid cards, Middel said. It later surfaced that about 200,000 cards, including from Magyar Telekom, were registered under one name, and a small number of those may have been used by terrorists, he said. DT, which already requires its German shops to check for IDs when selling prepaid cards, has created a task force to explore how to best combat the phenomenon, Middel said.

Hungary tightened its laws last year, citing the threat of terrorism after authorities disclosed that large quantities of SIM cards had been purchased in the eastern European nation under the name of a homeless person. They were then used for communication by perpetrators of the Paris and Brussels attacks in 2015 and 2016.

Phone companies will have to scrutinize the identity of SIM-card buyers and will only be allowed to sell them to foreigners who show up in person and present valid travel documents or a residency permit, according to the regulator. Telefonica’s German unit is open to discussing European coordination on the issue, Cornelius Rahn, a spokesman for the company in Berlin, said by phone.