I guess it would make sense if they were all jammed, though I'm not sure the fact that your phone didn't pick those up really proves this was the case? I have no idea how these work but I could totally imagine phones interpreting jammed signals differently from weak/nonexistent ones. Plus, I've had at least one that nominally supported all of those but in practice didn't really feel that way. You're probably right, just not sure you can deduce it from your phone in particular.