I walk my basenji off lead every day and she has a very good recall, better than my labradors even. No dog is 100% off lead and you have to be sensible - not walk them loose near roads or anywhere they can get into trouble, that goes for any dog! My labradors, as obedient as they are, will also chase after things but they will come back when they are called. Maya has chased after rabbits/birds/deer when they have rushed out of hedges or stuff and she always comes back.
I taught her recall by taking her out with my other dogs as soon as she was able to, she learned from them that when i call, you come over! And she would get treats and lots of fuss when she came back, and still does occassionally now just so she knows she is being good.
I dont agree that just because a basenji is a sighthound it shouldnt be walked off lead, i personally do not think it is healthy for a dog with the exercise requirements of a basenji to only be walked on a lead, but im sure some people will disagree with that. Im lucky to have a fully enclosed dog park to walk my dogs in (where i taught Maya recall) and also hundredss of acres of farmland which is where we mostly walk these days.
It certainly is possible to teach recall with a basenji, but you have to use common sense when walking them like any other dog.