Embodiments of the present disclosure provide a method and an entity for checking port consistency of NIDD message. A first aspect of the present disclosure provides a method performed at a first entity (100), comprising: receiving (S101), from a second entity, a non-internet protocol data delivery, NIDD, message including one or more RDS port numbers; and determining (S102) whether the one or more RDS port numbers are within a configured RDS port list. According to embodiments of the present disclosure, network resources for transmitting the invalid NIDD data may be saved, and undesired actions in the communication system may be avoided.