The Australian scrum-half signed for London Irish on a two-year deal in February 2013 but was released this summer after breaking a foot in pre-season last year.
However, pre-season knocks to Dave Lewis and Will Chudley have meant Baxter is keen to ensure there is sufficient cover for the start of the new Aviva Premiership season, which gets underway this Sunday with a trip to newly-promoted London Welsh (2pm).
Lewis is currently sidelined with an elbow injury, whilst Chudley was knocked out in the opening 90 seconds of last Friday's 26-6 pre-season win at Worcester Warriors. Chudley, however, is expected to be fit to face the Exiles this weekend.
Phibbs - who played 10 times, scoring one try during his previous spell at Sandy Park - is likely to get a run-out when the Exeter Braves kick-off their A League campaign next Monday at Saracens.
Baxter has said he wants to run the rule over the 32-year-old both in training and possibly that fixture before bringing him in as emergency cover.
“Pat’s down on trial with us," said Baxter. "Obviously he hasn’t played for a while with the injury issue he had last year, so he’s coming down and is training with us this week then we’ll make a decision on the length of time he stays with us.
“It’s a bit difficult for Pat because he’s not been on the rugby pitch in a competitive sense for a while so we’ll have a look at him and see how up to speed he is.
“With Dave Lewis having a relatively short-term injury, whoever we bring in has got to be up to speed pretty quickly.
“It’s an opportunity for Pat to get back on a rugby pitch and do some training and play some rugby, so we’ll have to see how he gets on.
“We’ll probably involve him in Monday night’s A game if he comes through training okay then we’ll make a decision based on that.”
