Despite the fact that Verizon's official specs for the HTC Rezound say nothing about GSM capabilities, some posters at xda-developers have spent the last month confirming that the handset does indeed work globally on GSM networks. The poster who kicked all this off discovered that when switching LTE on or off, there were options for "global mode" as well as "WCDMA only" and "GSM only." The UK-based poster popped in a SIM card from T-Mobile and was able to get the Rezound to place and receive calls, use the data connection, and receive texts — the only issue appears to be sending SMS messages. This problem apparently persists regardless of what ROM is loaded onto the phone, but it's still a boon for users who want to use this device internationally.
While Verizon might not admit it directly, there are a few clues that this phone could access global GSM networks — on the Rezound product page, Verizon notes the phone runs Qualcomm's MSM8660 processor, which includes both WCDMA / GSM and CDMA radios, making it technically compatible with networks around the globe. Verizon's also already confirmed that the LG Spectrum and forthcoming Droid 4 will support GSM roaming once the carrier completes some "network enhancements" — it wouldn't surprise us to see the Rezound join those devices when Verizon rolls this all out.