Unlocking phones - AT&T vs Verizon

[FillInThe_____]

Hey forum! I'm looking to buy a smartphone. I'd like to buy it outright, unlock it, and use it on the T-Mobile network. I know I need carrier permission to do this (I'm in the US), so my question is, which carrier (if either) will let me unlock their phone, and what is required for them to do so? For reference, here are some of the phones I'm looking at:

AT&T:
Sony Xperia TL - Prob. my preferred choice.
Pantech Discover - Maybe a bit wide for me, but I could work with it.

Verizon:
LG Spectrum 2 - Prob. my no. 2 choice after the Sony.
Droid RAZR MAXX HD - Nice, but too pricy. Also hard to find (though I haven't checked my local stores yet), and no removable batt. Not a deal breaker, but a useful feature none-the-less.

I'm willing to consider other phones. I'm also willing to buy pre-unlocked phones, if anyone knows a reliable seller, but my preference is a sealed, NIB retail device.

Extra Info:

I'm planning an overseas trip for late this year/early next, which is part of the reason why I want to unlock.

I have a friend with an AT&T account in good standing.

I chatted with a Verizon cust. service. rep last night, and she confirmed that Verizon phones are GSM compatible. I read somewhere that Verizon phones were SIM unlocked out-of-the-box, but the rep said they were locked to the Verizon network. Correct me if she's wrong on either of those points.

If you're interested, here are some other phones I looked at along with what I ultimately didn't like about them.
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T-Mobile:
Google Nexus 4 - No SD slot
LG Optimus L9 - Better features available for a bit more $$
Samsung Galaxy S III - Too big/wide
Samsung Galaxy S Relay - Too low resolution

AT&T:
LG Optimus G - Too big/wide
HTC One X+ - No SD Slot
HTC One VX - Xperia TL is a better phone for the same price*
Motorolla ATRIX HD - Bit too wide
Sony Xperia ion - More $$ than TL*

Verizon:
Droid DNA - No SD slot

*Based on online pricing
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Let me know if you have any questions. Thanks!

 

[Droidwerks]

Last time I was with Tmobile (which has been about 10 years ago) they were the best in the business with unlocking phones. I used their prepaid service, and back then once you'd been active for 90 days, they would give you the unlock code. Why not just buy the phone from Tmobile?

 

[FillInThe_____]

I know it's lame, but I don't really like any of the t-mobile phones. The LG Optimus L9 comes the closest, but the way t-mobile value plans work, you end up paying full price for the phone (down payment + 20 monthly installments). It's not a bad model, and I really like that they're doing this, but the result is that I can either pay $300 for the L9, or I can pay $450~$500 for something better.

AFAIK, most carriers require you to be with them for 60~90 day before you can request an unlock code, and not that it matters in this case, but they also limit the number of phones you can unlock in a year, typically 5 or so. AT&T has a very clear policy in their service contract (which, of course, I won't be signing), but I haven't been able to find anything concrete on Verizon.

Speaking of Verizon, I stopped by the store last night and got my hands on the Spectrum and the Maxx HD. I really liked the Spectrum, and I really did not like the Maxx HD. I also stopped by the AT&T store, but apparently they close ridiculously early, so I won't be able to get my hands on the Sony or the Pantech until later this morning.

Which brings me back to Sony. I didn't know this until last night, but apparently Sony actually caters to people just like me! If you go to the Sony Store, they sell manufacture unlocked devices. It seems that the TL is only available through AT&T, but that the T is available factory unlocked. As far as I can tell, the only difference between the two is that the TL is LTE capable (hence the L designation). Though the T is not available directly on Sony's website, I did find an e-bay seller offering the US ver, sealed, with full retail packaging. If I decide to go with this phone, that's the one I'm going to get. After reading several reviews, though, I'm a bit less enthusiastic.

So it looks like it's going to come down to Verizon. If I can find out whether or not the Spectrum can be SIM unlocked and used on the T-Mobile network, I can decide if I want to go with that or the Xperia T. I'll probably call up Verizon support (as opposed to their sales support) and see if they have any insights.

 

[FillInThe_____]

I ended up getting the Spectrum 2. Got my SIM yesterday, and aside from a bit of trouble getting past the activation screen, everything went pretty smooth.