identities of MSC/VLRs, such as MSC/VLR 114$_{,}$ MMEs, such as MME 116$_{,}$ and foreign HLRs or HSSs, such as HLR/HSS 118$_{.}$ 

A dynamic learning and screening module 120 populates the entries in DPT 108 and DRT 112 and screens traffic using static and dynamic data in the security database. Dynamic learning and screening module 120 may operate in different modes to learn, test, or screen messages from foreign mobility management nodes. The different modes described herein include off mode, learn mode, test mode, and active mode, each of which will be described in detail below. 

As stated above, routing node 100 may dynamically learn identities of foreign nodes and create new entries in dynamic profile table 108 for the new node identities. A new entry is an entry for which no rule is provisioned in static profile table 106 that classifies the new identity as whitelisted or blacklisted. If there is no entry for an HLR, HSS, MSCA/LR or MME in static profile table 106 where the node is classified as blacklisted or whitelisted, the node identity is considered as new and is dynamically learned by adding an entry to dynamic profile table 108$_{.}$ The dynamically learned node identity will initially be classified as graylisted and may subsequently be classified as whitelisted, blacklisted, or graylisted, depending on results of validation testing, which will be described in detail below. 

As stated above, dynamic learning and screening module 120 of routing node 100 may be capable of operating in different modes with respect to dynamic learning. These modes are as follows: 

Off mode: No dynamic learning is performed; messages are allowed or blocked based on configured rules in static profile table 106 and dynamic profile table 108$_{;}$ 

Learn mode: Learn new mobility management node identities; validation testing of newly learned nodes is not performed; classify all newly learned node identities as whitelisted; 

Test mode: Learn new mobility management node identities; perform validation testing of newly learned mobility 

