The Reconfigurable Intelligent Surface (RIS) can be considered a key part of the backbone of 5 G and 6 G communication mainly due to its electromagnetic properties for controlling the propagation of the signals in the wireless channel. While substantial research exists on single-operator RIS optimization, the multi-operator scenario introduces unique opportunities and complexities that require systematic investigation. The implementation of multi-operator RIS systems presents significant technical obstacles, such as inter-operator interference and the complexity of coordinating resources. A critical challenge arises during channel estimation, where the concurrent reflection of pilots by uncoordinated RIS introduces a new form of pilot contamination effect. This crossoperator RIS interference creates a performance ceiling that cannot be overcome by increasing transmit power or adding the number of training pilot signal. To mitigate this, implementing orthogonal RIS configurations between operators during pilot transmission is conveyed. Consequently, coordination between multiple operators is essential. © 2026 IEEE.