dynamically learning time parameters usable for velocity checks between old and new foreign mobility management nodes. 5. The method of any preceding claim wherein operating the telecommunications network routing node in the active mode includes receiving messages from foreign mobility management nodes, performing lookups in the security database using mobility management node identities extracted from the messages, and blocking or passing the messages based on the dynamically learned security status for the node identities stored in the security database. 6 . The method of any preceding claim wherein the telecommunications network routing node comprises a signal transfer point (STP). 7. The method of any one of claims 1 to 5 wherein the telecommunications network routing node comprises a Diameter signaling router (DSR). 8. The method of any preceding claim comprising, providing, in the security database, a static profile table for overriding dynamic learning of foreign mobility management node identities, wherein the telecommunications network routing node routes or blocks messages from foreign mobility management nodes based on the security status stored in the static profile table. 9. The method of any preceding claim wherein operating the telecommunications network node in the test mode includes dynamically learning the security status of a foreign home location register (HLR) or home subscriber server (HSS). 10. The method of claim 9 wherein operating the telecommunications network routing node in the active mode includes using the dynamically learned security status of the foreign HLR or HSS to filter traffic from the foreign HLR or HSS. 11. A system for dynamically learning and using foreign mobility management node information for telecommunications network security screening, the system comprising: a telecommunications network routing node including at least one processor and a memory; a security database located in the memory; and