Cammy won the last of his four caps as a replacement against France during the 2000 Six Nations campaign.
He'll fly out to Australia on Thursday evening and is unlikely to be involved in Scotland's second Pool B outing against the United States in Brisbane on Monday.
Cammy told the SRU website: "Obviously my heart goes out to Andrew. Playing rugby for as long as I have you know what it means when you miss out on an opportunity to play in the World Cup."
"I decided to throw in my lot with Glasgow and I knew that if I could get myself playing well week in, week out for Glasgow then other things could happen."
Hugh Campbell was pleased about Cammy's return to the Scotland squad. "It's great for Cammy," the Glasgow coach said. "We're all delighted that he's made the next step back up."
"Cammy is in fine form and we've been monitoring him closely," said Ian McGeechan. "If required, he can also play at the other side of the scrum, which is one of the criteria we used when making our decision.
"Donnie Macfadyen was very much in our thoughts but after consultation with the Glasgow doctor and physiotherapist it was felt Donnie was not going to be fit to travel because of a shoulder injury. We feel Cammy meets our requirements."