Last term he spent time on loan at Morecambe, where he made three appearances and conceded six goals.
Shrews boss Jimmy Quinn said that he felt the scouse keeper was unlucky after being injured early on last season. He said: 'Ian was very unlucky here. At the beginning of last season I had to bring in Scott Howie, who did very very well for us.' The development of teenager Joe Hart, who recently saved a penalty, also contributed to Dunbavin's departure.
The keeper told the Shropshire Star: 'I'm just relieved to know that I'll be playing first team football again because at this stage of my career I can't afford to stand still'. Similarly, Town can't afford to be bankrolling three keepers' wages!
Halifax seemed pleased to get their man. Shaymen bos Chris Wilder said: 'We are delighted to have got him.
'He is an experienced number one. He is not a young keeper making his way in the game or at the veteran stage of his career. He has had plenty of experience in the Football League.'