Hello, If you would like to see if your phone is currently utilizing Verizon's "XLTE" network, it is quite simple to do so on your iPhone. Go to the phone app and dial "*3001#12345#*", click on "Serving Cell Info". In the list you will se "Freq Band Indicator" and a number to the right. This is the LTE band your phone is currently utilizing for data. Verizon's original LTE network is the 700Mhz LTE band 13, the new "XLTE" network is 2100/1700Mhz AWS LTE band 4. On that same page you should see "Upload Bandwidth" and "Download Bandwidth". If you are on Band 13, you should see 10Mhz up and 10Mhz down. If you are on Band 4, you may see 20Mhz up and 20Mhz down. Several Markets west of the Mississippi don't have the full 20x20 bandwidth and you may see a 10x10 or 15x15 LTE network. The more bandwidth, the more speed you will have. Thus a 10x10 network will give you a max theoretical speed of ~70Mbps while a 20x20Mhz network will give you ~140Mbps.
LTE band 4 is AWS spectrum meaning it operates on the downlink at 2100Mhz and uplink at 1700Mhz. This is a high frequency and high frequencies do not have very good in building penetration unless you are close to the cell site. You may notice that your phone will drop to LTE band 13 when you go indoors as the 700Mhz low frequency spectrum can adequately penetrate building materials to give you better service.
Here is a list of the LTE networks some US operators use today:
Verizon: 10x10 Band 13 (main band), 20x20 Band 4 (limited areas)
AT&T: 10x10 Band 17 (main band), 5x5 Band 2 (limited), 10x10 Band 4 (limited), 5x5 Band 5 (very very limited)
Sprint: 5x5 band 25 (main), 5x5 Band 26 (for in building cov.), 40Mhz TDLTE Band 41 (sprint "spark")
T-Mobile: 10x10 Band 4 (main; will be 20x20 in former MetroPCS areas after shutdown of Metro network), 5x5 Band 12 (planned to build in 2015 using 700Mhz A block purchased from Verizon recently)