Published Wednesday, 29 January 2014
Callacher is now free to play for the Blues. (© Pacemaker)
It comes after the two Belfast sides reached an agreement on his transfer.
Speaking to the Linfield website on Tuesday, Jeffrey said: "I'm absolutely delighted that Jimmy Callacher is now able to join us tonight.
"He's a young man who I've watched over a long period of time and who's impressed me, incrementally and increasingly with his performances.
"I've been impressed not just with his footballing ability but by his desire to win and his integrity, as well as his sheer professionalism. I've been monitoring his performances and progress for a number of years now and it's great to welcome him on board at training."
Callacher, who came through the youth ranks at the Oval, had signed a pre-contract agreement with Jeffrey's side.
His contract with Glentoran had been due to finish at the end of the season and Callacher would have been free to move to Linfield then.
Reports suggest the deal for the 22-year old cost Linfield between £8,000 and £10,000.
© UTV News