DL doesn't recognise that if shortened to 'phone then the apostrophe to indicate the omission of the tele is a valid and older option - though sussex uni states "Writing things like... 'phone will, not to mince words, make you look like an affected old fuddy duddy who doesn't quite approve of anything that's happened since 1912. nothwithstanding my fuddy duddy-ness I should not be marked incorrect for my 'phone!
If telephone is accepted, then almost by definition 'phone (with apostrophe) should be accepted - though I'd have to agree with the essence of the Sussex Uni argument.
I'd also be tempted to say that if you can bring yourself to write Sussex uni.... shall we say the argument for punctuation of phone is weakened ;-)
Pop60, right about typing sussex uni, but only if I was arguing for the requirement of the ', not for its acceptance. I learnt 'phone formally at school whereas I picked up uni as an informal abbreviation later. Also isn't it interesting that when abbreviating by truncation a full stop is used instead, for example: abbrev..