Czechia

In spite of being a smallish market with 10 million population, Czechia has more than 14m subscribers, one of the highest penetration rates in the world. The operators, especially T-Mobile and Vodafone have been filtering heavily and actively shutting international routes down, or imposing high interworking fees. 

Sender ID: 

In line with local regulations, the Sender ID will be changed in compliance with operator restrictions to ensure delivery.

Sender IDs are all overwritten generally to a local shortcode but also occasionally to an alpha or random numeric sender.