I have an SPA-2102 that was setup by Lingo. I would like to provision this ATA for another provider, but the ATA is in it's default configuration, no passwords and it's still locked. Can this ATA get unlocked?

SOURCE: LinkSys SPA 2102

try this out
power on your linksys
then pick up the phone connected to that linksys
no dile tone required
dial ****
when it says configuration menu
type 73738#
if ask for password then nothing can help you buddy
and if it says press 1 to save then press 1 and your device is reset with factory default

SOURCE: LINKSYS SPA-2102 CAN NOT FACTORY RESET, PASSWORD REQUIRED!!

You need to:
1) figure out where it's going for config file updates (e.g. http://ip address/path/filename (wireshark highly recommended for this)
2) once you have the filename, you need to find a "broken" copy of that CFG file. You may be able to use the broken sunrocket one (google linksys2102-sunrocket.cfg)
3) setup a webserver to it appears to be at the ip address above (there are a number of ways to do this - google sunrocket 2102 for some step-by-step instructions.
4) reboot the SAP with the DTMF codes

That all seem like too much? Then go to broadband reports.com and PM DogFace05 - he can remotely unlock your 2102, but there's a fee.

SOURCE: password of linksys spa 2102

The Linksys comes with web admin access disabled.

To enable it, pick up phone, dial **** then 723646# , when asked for password, dial 78778839# , when asked for value dial 1# then dial 1 to save.

Then, go to »192.168.0.1/admin/voice/advanced , enter user and password.

If you did a factory reset, you will need to call Linksys technical support.

SOURCE: I just bought a SPA-2102 NA, is it possible for a

Yes - if you set provision enable to "yes" or resync from SIP to yes, they can then set your SPA to download a configuration file with an admin password you don't know.
Seems pretty rude (as in legally actionable) if they have actually done this.