It should be mentioned that IFTX takes considerable liberties with the WSJT-X software concept. I did make some contacts with it, but it needs some changes to be truly useful.
Operational: The software will ONLY let you call stations that are literally calling CQ. You cannot reply to stations sending the 73 period who often get another call immediately from others and may not literally call CQ any time soon. And if you reply to a CQ and the station comes back to someone else, rather than continuing to call (remember, you are probably not on his frequency) you get a big, obnoxious red banner that says “LOST” and you will have to wait for that station to call CQ again before you can call again. WSJT allows you to initiate a call to anyone you can receive at any time, which is how FT8 should work.
Technical: In WSJT there is a split mode that shifts your center VFO frequency if you are calling below 1500 Hz. You keep your relative position in the 3kHz passband, but the radio changes TX center frequency. Why? Because the idea is to keep harmonics of your audio frequency outside the 3kHz passband of the FT8 segment where they will be suppressed rather than transmitted over the air. Example: if you are transmitting on 1600 kHz, the second harmonic would be 3200 kHz, safely suppressed. But if you are on 800 Hz, the second (1600 kHz) and third harmonic (2400 kHz) are NOT suppressed and are transmitted (at somewhat lower power), but are still transmitted over the air. WSJT has a mode called “fake it” that provides this if you don’t have rig control to move the VFO on transmit. I would definitely operate using TX frequency above 1500 kHz with this software. To be a good neighbor to your fellow hams…
While it “works” and is cheap, IFTX is not really ready for prime time, IMHO.
