Coach Gordon Strachan has turned to the left full-back as cover for injury doubts Lee Wallace and Danny Fox for Friday's clash in Zagreb.
And Hammell admits he was pleasantly surprised when Motherwell boss Stuart McCall, who is part of the Scotland set-up, called him with the news.
"People might say there have been a lot of call-offs but that doesn't matter in the slightest to me because it's a fantastic honour to represent your country," he said.
"I was thrilled to bits when the gaffer rang me on Wednesday. At first I thought he was winding me up then he said he was deadly serious and that Gordon wanted to know if I was available.
"I had no hesitation in telling him in the most emphatic of terms. When Gordon rang me, I was delighted to accept.
"The ironic thing is I'm doing my coaching badges at Largs and when the media interviewed me earlier this week the international scene came up in the discussion."