This entails:
* Adding S1AP paging messaging to the MME.
* Adding the Downlink Data Notification, Donlink Data Notification Acknoledgment, and Downlink Data Notification Failure Messages.
* Adding the logic at the GTP-U to detect that Downlink Data notification needs to be sent.
* Proper handling of the new GTP-C messages at the MME GTPC and SPGW GTPC classes
* Add queuing mechanisms at the GTP-U while waiting for paging response. Queue is flushed when paging fails (timeout or other).
* Make sure eNB's SCTP information is properly stored.
* Make sure UE's GUTI information is properly stored.