Dallas-based Entrust, a developer of secure certificates and other related products, said this morning that the firm 's customers can now use the popular Apple iPhone to connect to secure networks. According to Entrust, the latest iPhone operating system supports X.509 digital certificates from the firm, via the built-in, Cisco IPSec VPN client in the phone. Entrust said that the capability provides a high-level of IP-based encryption for firms who want to use Apple iPhones for connecting into corporate networks.