As a dispatcher for a large UK police force who has just recently switched to TETRA/Airwave I fail to see how it can take another two years+ for the ambulance service to switch over to it, the infrastructure is already in place all over the UK so no delays with that, I'd say all you need is to fit the radios in the vehicles (We use these http://www.sepura.com/products-features.php?id=34), they have in-built GPS modules which report position back to mapping terminals in control rooms. It supports text messaging and they have serial outputs so i'd say it would hardly take alot to connect them to your existing MDT's for patients details, I have found the voice quality second to none. Emergency buttons which you press and you get 20 seconds of 'open mic' to shout whats the problem and the dispatchers terminal lights up like a christmas tree and reports GPS position to the map. You can also have private radio-radio calls to send sensitive info/sandwich order/bollockings. I've never had a problem with inter-force comms either, In training we spoke to a few officers in south wales which was'nt bad considering we were in the midlands. You could have your own police hailing talkgroup to summon immediate assistance when required, rather than ambulance tell ambulance control, ambulance control ring police, police then send job to divisional control room then send officers which could be wasted seconds. And when your in the system in the worst case scenario if ambulance control room became unavailable the fuzz could make do dispatching ambulances to jobs in the meantime whilst alternatives are sorted out and vice-versa for fire brigade. Personal radios might be where it gets a touch expensive if they have a habit of going walkies, £800 a go could add up fast, but with in built GPS as long as they are turned on once in a while it won't be long before they are tracked down! The personal radios also have an area under the battery for a SIM card which I would imagine turns them into a mobile phone but I don't know how this works A year tops and they could do it but they will spend it on everything else except for front line safety, A bit long winded but having swapped from a really bad (that is unless you wish to hear Russian Trawlers instead of officers) UHF radio system to one which has all the bells and whistles I think its fantastic.