imei check said server down

Activation failed when a communication with Apple servers was expected.

(Official unlocks rely on having Apple send your device a list of approved SIMs during activation, and thus having the unlocker request Apple to approve your device for all cards).

This sounds like an occasional, temporary error: if it persists, I would be inclined check the hosts file on your computer to make sure it isn't redirecting any Apple servers, although I haven't ever heard of a modification that would break activation in this way.

The "043" in your serial number stands for "made in year (201)0, week 43": you can use the jailbreak tool redsn0w to install and then remove the iPad baseband, enabling you to software-unlock your iPhone as described in this guide: http://www.redmondpie.com/how-to-downgrade-iphone-3gs-3g-06.15.00-to-05.13.04-baseband-for-unlock-and-working-gps/