Occasionally, particularly with Southern English accents, 'too' and 'tree' are indistinguishable. For that reason I never say 'tree', indeed I think it would be better pronounced 'free'. 'Fife' is superfluous, 'niner' I do say but not all the time. A lot of this has to do with a time when radios were not as good as they are now, or with e.g. HF communications. In reality you can just carry out a normal conversation and everyone will know what you're saying.