A method for processing messages in a mobile communications network, the method comprising: at a first network node: receiving a first message relating to a communication in a mobile communications network, the first message including a called directory number; performing a lookup in a first database based on the called directory number to determine whether a called party has been ported out of a first network and to determine a migration status of the called party; in response to determining that the called party has been ported out of the first network, formulating a first reply message including first routing information from the first database, the first routing information indicating a second network to which the called party has been ported; and in response to determining that the called party has not been ported out, formulating a second reply message including second routing information from the first database, the second routing information corresponding to the determined migration status; wherein formulating a second reply message including second routing information corresponding to the determined migration status at the first node comprises: determining whether the directory number is registered according to a first application layer mobile signaling protocol; and in response to the directory number being registered in the first application layer mobile signaling protocol, formulating the second reply message to include second routing information indicating a node in the first network that corresponds to the first application layer mobile signaling protocol and that is serving the called directory number. at a first network node: receiving a first message relating to a communication in a mobile communications network, the first message including a called directory number; performing a lookup in a first database based on the called directory number to determine whether a called party has been ported out of a first network and to determine a migration status of the called party; in response to determining that the called party has been ported out of the first network, formulating a first reply message including first routing information from the first database, the first routing information indicating a second network to which the called party has been ported; and in response to determining that the called party has not been ported out, formulating a second reply message including second routing information from the first database, the second routing information corresponding to the determined migration status; receiving a first message relating to a communication in a mobile communications network, the first message including a called directory number; performing a lookup in a first database based on the called directory number to determine whether a called party has been ported out of a first network and to determine a migration status of the called party; in response to determining that the called party has been ported out of the first network, formulating a first reply message including first routing information from the first database, the first routing information indicating a second network to which the called party has been ported; and in response to determining that the called party has not been ported out, formulating a second reply message including second routing information from the first database, the second routing information corresponding to the determined migration status; wherein formulating a second reply message including second routing information corresponding to the determined migration status at the first node comprises: determining whether the directory number is registered according to a first application layer mobile signaling protocol; and in response to the directory number being registered in the first application layer mobile signaling protocol, formulating the second reply message to include second routing information indicating a node in the first network that corresponds to the first application layer mobile signaling protocol and that is serving the called directory number. determining whether the directory number is registered according to a first application layer mobile signaling protocol; and in response to the directory number being registered in the first application layer mobile signaling protocol, formulating the second reply message to include second routing information indicating a node in the first network that corresponds to the first application layer mobile signaling protocol and that is serving the called directory number.