[T-Mobile LG G2x] jwells777:
Unfortunately, as suggested by Core Memory above, I have not been completely successful in this investigation; however, I will post what I discovered along the way for the benefit of others. Perhaps someone else can pickup where I left off and get things working.

First, a summary of the final status:

1) Updated NV Items to enable 850 MHz and 1900 MHz bands

2) Was able to see 850 MHz UMTS providers under the "Search Available Networks"

3) It appeared that a connection was being made to the UMTS provider based upon both the signal strength monitor in "About phone" and the Engineering Mode page that provides data regarding 3g connections

4) In the Engineering Mode page, it seemed that the device was trying to connect (login?) to the network but was not being successful with the login

5) When at the lock screen and forcing the connection to the 850 MHz UMTS network, the "Emergency Only" text appears further suggesting that the connection is working but that my configuration for the network may be wrong.

6) No 1900 MHz providers ever appeared in the network lists while searching. I am not sure whether this is because this band was not functioning or if it was because no such provider existed since I am not terribly familiar with the coverage where I am currently at.

For those who wish to follow this path and test in their own local markets, please see the following steps required to reach this point:

Tools needed:

1) QPST 2.7 (Build 366 or later)

2) QXDM 3.12.714 (or later)

Steps:

1) Install necessary tools on your computer.

2) Enable USB debugging (Settings-->Applications-->Development)

3) Connect phone to PC

4) In the hidden menu (1809#*999#), ensure that Port Setting is configured to CP USB.

5) Launch QPST Configuration

6) Under Ports, select Add New Port.

7) Locate your device and enable the port. (NOTE: There may be two ports available to you here. I believe that you want to use the one that is for Serial / USB/QC connections.

8) From QPST Configuration, launch the "Software Download" tool under the "Start Clients" heading.

9) From here, create a backup QCN file. This backup may or may not enable you to recover from making a mistake later. Also, there is alot of information in this file if you care to navigate through it.

10) Launch QXDM Professional.

11) View-->New-->Common-->NV Browser

12) Options-->Communications-->Target Port (Select your phone)

13) The previous step should have "enabled" the NV Browser lower pane

14) Read and record the following NV Items

a) (441) Band Class Preference (0xFFFF)

b) (946) Expand Band Preference 16 to 32 Bits (0xBFFF)

c) (2954) Bits 32 to 63 of Band Pref (0xFFFFFFFF)

d) (1877) RF Band Configuration (0x0000000002680380)

15) Update item 1877 per discussion below

16) Reboot phone

17) It may be necessary to configure the Modem Setting in the hidden menu to reflect the additional bands.

NV Item configuration discussion:

I am no mobile phone programming expert (< 4 hours playing with them at this level to date); however, as near as I can tell, item 1877 configures the hardware of the modem while items 441, 946, and 2954 appear to be some type of masking bits regarding what bands to prefer. As such, I believe that the original value of item 1877 enables the following RF bands:

(Bit:7) GSM (1800)

(Bit:8) GSM Extended GSM (E-GSM)

(Bit:9) GSM Primary GSM (P-GSM)

(Bit:19) GSM (850)

(Bit:21) GSM (1900)

(Bit:22) WCDMA Band I (2100)

(Bit:25) WCDMA Band IV (1700)

If you set 1877 to 0x000000006E80380, it should enable the following:

(Bit:7) GSM (1800)

(Bit:8) GSM Extended GSM (E-GSM)

(Bit:9) GSM Primary GSM (P-GSM)

(Bit:19) GSM (850)

(Bit:21) GSM (1900)

(Bit:22) WCDMA Band I (2100)

(Bit:23) WCDMA Band II (1900)

(Bit:25) WCDMA Band IV (1700)

(Bit:26) WCDMA Band V (850)

If anyone succeeds in getting any further using this information, I would be very curious to hear of your success. Also, please do share with the community such that we can collectively move forward.

Disclaimer: I accept no responsibility for any damage that you may cause to your phone with these tools or procedures. Please note that these tools give you fairly low-level access to your system that enable you to significantly mess things up. Further, please note that modifying the radio bands on this device may void your warranty and/or be in violation of local regulations as set by your local authority (e.g., the FCC).