Forster told Celtic's official website: "I'm obviously delighted and happy to get the call-up. I'm excited as well and just looking forward to meeting up with everyone really.
"It's a great opportunity and a great chance to test myself against some great players.
"I got a call from the gaffer yesterday to let me know he thought it was going to happen and then I found out for definite today so I'm thrilled."
Forster's inclusion is mainly due to Jack Butland's demotion to the Under-21 team.