The Saints loanee has impressed on loan at League 1 side Barnsley this season, doing enough to be rewarded with a call-up by Chris Coleman.
Isgrove has won five Under-21 caps for Wales, but has not featured for his national side since 2014.
Wales take on Steven Davis's Northern Ireland on Thursday 24th March, with a kick-off time of 7.45pm GMT.
They then travel to Ukraine on Monday 28th March, with a kick-off time of 5pm BST, as they continue their EURO 2016 preparations.
Elsewhere, Virgil van Dijk and Jordy Clasie have been included in the final Holland squad for upcoming matches against France and England.