The Secure and Resilient Mobile Network Infrastructure solicitation was posted on April 22. DHS is looking for solutions to potential security gaps in air interfaces between mobile devices and the radio access network, between cell towers and base stations, virtualized segments of the radio network and core network that supports it. The announcement also mentions the side-channel network telecommunications use to send network information called Signaling System 7 (SS7). Mobile security is top of mind for the Cybersecurity and Infrastructure Security Agency at DHS. The Secure and Resilient Mobile Network Infrastructure solicitation is also looking to address gaps in encryption in existing 4G networks, in which user traffic is not "necessarily" encrypted as it moves through wireline backhaul networks. The program is also looking to improve visibility into government mobile devices that are outside federal firewalls and Trusted Internet Connection networks and to help guarantee that emerging 5G network security architecture takes government needs into account.