The Chelsea defender announced his decision on the eve of an FA hearing into his alleged racial abuse of Anton Ferdinand, having been cleared of a racially-aggravated public order offence at Westminster Magistrates Court back in July, stating his position in the national team set-up had become "untenable".
The revelations leave Roy Hodgson with some big decisions to make regarding team selection, with Jagielka among a number of names being touted as Terry's potential replacement.
Round is adamant the Toffees' defender is good enough to make the step up on a more permanent basis, although he admits others will also be keen to fill the void left by the Chelsea skipper.
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"Without doubt it is a chance for Phil to stake a claim, it is a terrific opportunity, it really is," he told reporters.
"He has speed, awareness, and is a very good defender one versus one - which is very important in international football.
"He is also starting to show the composure now which has taken him a while to come to terms with: being able to become really comfortable on the ball, taking the ball from the goalkeeper and building from the back.
"He was starting to show that for Everton and he was starting to show it for England. There will be one or two thinking they have an opportunity, like Gary Cahill at Chelsea.
"It is great opportunity for Jags and if he gets it he will take it. He is ready for it - I know that - and he feels he can step up that level.
"He certainly has the talent and ability, he just needs to get in now and establish himself."
David Moyes' assistant has worked with Terry in the Three Lions camp in the past, and admitted he was shocked to hear of the 31-year-old's decision, indicating he will be a big loss to Hodgson.
"I was surprised, like everyone else. I worked with him at England for a couple of years and I found him a terrific captain, whole-hearted and 100% every day, every game," he added.
"He will be missed because he's a top player and a top defender."
Newcastle centre-back Steven Taylor is another player that it has been suggested deserves an opportunity to feature on the international stage after Terry's retirement.
Magpies boss Alan Pardew believes the 26-year-old, who made 29 appearances at England under-21 level but has never been capped for the senior side, has the potential to go on and play for his country but adds that this could be the wrong time, considering his recent achilles injury.
He said: "Steven has ambitions to play for England and I think he has a lot of credentials for that.
"But I think it's too early for him at this stage because he is only just back from a long injury.
"Probably Steven needs another good half-season under his belt to be considered for England, I would think."
Pardew also thinks Hodgson will be hampered by Terry calling it a day for the Three Lions, especially because of the lack of English players in the Premier League.
He continued: "I just know for the manager of England, it's a blow because he is a great player and the pool isn't great for English players at the moment and the team."