Telfer, who followed Gordon Strachan to Southampton and then Celtic, was unemployed after leaving AFC Bournemouth last season.
Capped by Scotland, Telfer had picked up an injury which was going to keep him out for the rest of the season after making 24 appearances and with The Cherries in dire financial trouble, Telfer opted out of the rest of his contract which expired in June.
He has played with McAllister at Highfield Road and is line to start for Leeds in their games at Bray Wanderers and Galway United.
Meanwhile, Craig Reid has two games to make an impression at Accrington Stanley. Having left Cheltenham due to a lack of first team opportunities, the Coventry born striker has already played two pre-season matches for Stanley against Darwen and Cammell Laird and is expected to feature at Rossendale tomorrow and against Burnley on Saturday.
This evening he scored for Oxford United in a 4-0 win at Banbury with his first touch in a ten minute spell.
Patrick Suffo is on trial with Walsall. The striker scored twice against Worcester City the other night.
Tom Bates has joined Atherstone Town. The midfielder was at Coventry Sphinx last season.