Both anti-spoofing measures apply, if you have issues contact your service provider

From 1 July 2024, the condition for the operation of public communications networks and the provision of electronic communications services set out in the amendment to the general authorisation No. VO-S/2/04.2024-1 (in CZ only) is effective. According to this condition, which aims to substantially reduce the negative effects of spoofing, an analysis of how the calling subscriber is identified in the signalling message of a call coming from abroad will be carried out at the points designated for connecting calls from abroad to the Czech Republic. The analysis will evaluate whether the subscriber is marked with a certain type of so-called Czech number (with the area code + 420) and if so, the call will not be connected. In rare cases, even calls that are legitimate may not be connected - the implementation of the measure may occasionally cause difficulties. In such a situation, subscribers to electronic communications services should contact their service providers in the first instance, and only if unsuccessful, they should contact CTU.

As of 1 June 2024, a condition specifying the content of the signalling message to identify the calling subscriber so that no meaningless information is given is already in effect.