It is rebranded and sold as the O2 Xda Cosmo, the T-Mobile Dash,[1] the HTC S621 for Rogers Wireless in Canada, the HTC S621 for Suncom Wireless in the lower-eastern United States, the BT ToGo (as part of the BT Total Broadband Anywhere package), and the Dopod C720W.

[2][3] The device runs the Windows Mobile 5 and 6 Smartphone Edition operating systems (AKU 3.0).

[6] T-Mobile initially shipped Windows Mobile 5 on all Dash devices but began offering existing Dash owners the ability to update to Windows Mobile 6 on May 4, 2007.

[7][8] Version of Windows Mobile 6.1 such as Kavanna's and Ricky's are available but not supported by T-Mobile.

[citation needed]http://forum.xda-developers.com/showthread.php?t=560495 The phone supports Bluetooth 2.0 without EDR[10] and could support these profiles: New firmware versions disable nearly a half of these profiles, including FTP according to the pre-commercial review.