remote serial console (IP to Serial)

Recently I have taking over the responsibility of managing about 18 remote routers and firewalls. None of these have a console port for 'out of band' access accessible today. Most sites has available IPs between the ISP and us (typically a /29) or a backup DSL connection available for use. I'd like to purchase a IP to Serial port device I can use for each location in the event I lock myself out. The requirement would be an Ethernet port, a serial port, and SSH. Anyone have any recommendations on something like this? thanks much, greg