Hello,
It seems that the current practice is to use a DSL line, as opposed to a modem, for accessing an OOB a console server at a remote colo. From a security standpoint, what do people generally do - trust the console server, repurpose an old linksys box from my house or put in a full firewall?
Eric 
I have juniper SRX110s that use the magic new multi site IPSec thing.
There are hardware solutions for this type of install. Often it is
best to add/create networks for access from multiple points at once.
My suggestion is
http://www.lantronix.com/it-management/branch-office/securelinx-slb.html
Thanks for starting this discussion Eric. We're just starting to look at upgrading our oob console network and wondering how to provide access from LAN based application monitoring platforms. We're currently looking at installing a VPN appliance between our production network and the "oob network".
-Steve
+1. This is the way to roll OOB, CPE (Cisco ISR, Juniper SRX), RS232
console server (opengear, avocent) and switch if you happen to have modern
gear which support proper OOB like Nexus7k, and not enough ports in the
CPE.
OOB CPE could be reused for other functions to justify cost, like DCN
router, both SRX and ISR have models doing CLNS routing.
With correct CPE, same CPE can do 3G, ADSL and ethernet, depending on what
is available in given site.
Some RS232 console servers do deliver subset of needed features, like 3G,
IPSEC and Ethernet might be there. But that does not mean that it'll be
OPEX nor CAPEX chaper to try to do it all in one box.
My preferred OOB solution is cellular where possible. (Many companies make
such a dedicated product, or roll your own).
Most cellular providers can provide a private APN with private IP addresses
delivered back to you via a VPN tunnel. In many cases, telemetry (IE: 50Mb
or less per month) data plans cost much less than DSL lines or analog
lines. In some installations, it's also diverse to backhoe accidents due
to it not riding the same copper bundle.
Besides, it's easy to install and you don't have to deal with the copper
analog handoff.
Otherwise... DSL and IPSEC vpn also works. Analog is in the last option
for me.