After two poor away performances in defeats at Leicester and Coventry, hopes weren't high amongst the home faithful as Town faced a West Brom side who hammered them 4-0 at The Hawthorns earlier this season.
But, Fortress Portman Road proved unbreachable once again as Town extended their unbeaten home streak to 17 games - 15 wins and two draws - thanks to headers from defenders David Wright and Jason De Vos.
Phillips had a great chance on 11 minutes from a Zoltan Gera cross, but didn't connect cleanly with his volley and Neil Alexander palmed it over before Pablo Counago split the visiting defence but Jon Walters blazed over.
Ishmael Miller, on his first start after six weeks out with a knee injury shot wide for West Brom, before a neat Town move involving Counago, Walters and Liam Trotter ended with a great block on Walters by Paul Robinson.
Miller wasted a great chance to put the visitors ahead on 25 minutes when Jonathan Greening sprayed a great ball out to the left wing and Gera delivered a fine cross to the back post, where an unmarked Miller headed over.
Dean Kiely parried a firm Danny Haynes shot before a great piece of skill by Counago almost created a goal for Town, when he spun on to a Wright throw and from 20 yards curled the ball against the post with Kiely motionless.
Phillips had the ball in the net for West Brom on 37 minutes from a Gera pass, but he was offside and then a minute later he tried his luck with a dipping 25-yarder which clipped off the top of the crossbar.
The second half got off to a cagey start with few chances at either end, with probably the best falling to Phillips who struck his shot firmly on the turn from 15 yards but straight at Alexander.
Phillips and Miller were then replaced by Craig Beattie and Roman Bednar on 66 minutes, but the replacement pair rarely troubled the home rearguard in the way the starting two had done.
Walters shot wide and Kiely halted a firm Trotter shot before Town went ahead on 75 minutes with a flowing move started and finished by Wright, who raced from left-back to glance home at the near post from Trotter's pinpoint cross.
Bednar fired home a minute later from James Morrison's cross but he was offside and Town could have sealed the points a minute later, as Sito set up Counago whose low shot was parried by Kiely, who then also saved Sito's follow-up.
However, Town sealed the points with a simple goal on 84 minutes as Gavin Williams lifted a free-kick to the far post where Ipswich had three players against one West Brom defender and skipper De Vos got there first to head home.