So to sum up then, options are,
1: Use your phone to send text messages,
2: Buy whatever number of hand-held "walkie-Talkie's" need for formation flights?
3:Rewire the aircraft's inter-com/yoke with exta PTT button so you can attach the above "walkie-Talkie"
4:Use signal flags
5:Carrier pigeons
6:Signal mirror's
7:Smoke signals (no that would be really stupid)
8:Pick a recently closed aerodrome (there are a fair few) and use theirs. Ipswich has always been my favourite. Solved...
9: Petition the CAA/Ofcom for a reality check and allocate a frequency.................
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