B&I Lions legend answers Scarlets SOS
Phillips hung up his boots at the end of last season after a glittering career featuring 94 Wales caps and five British and Irish Lions Test appearances.
But the 35-year-old, who also played for Cardiff, Ospreys, Bayonne, Racing 92 and Sale, is set to make a short-term return to action with Scarlets.
Scarlets have named Phillips in a 27-man squad for their Pro14 games in South Africa against the Southern Kings on Sunday and the Cheetahs six days later.
Regular Scarlets scrumhalves Gareth Davies and Aled Davies are currently with Wales for their Tests, while the Llanelli-based region have seen Wales Under-20 international Declan Smith sidelined by injury.
"We only have one of our four contracted scrumhalves available through injury and international call-ups," Scarlets head coach Wayne Pivac said.
"We looked at the nines available to us within the region, and Welsh-qualified players in the Championship, but they were unable to travel due to work commitments and club commitments.
"We are delighted that Mike has been able to answer the call and will be joining us in South Africa."
Scarlets squad:
Forwards: Tadhg Beirne, Will Boyde, David Bulbring, Jack Condy, Steven Cummins, James Davies, Taylor Davies, Dylan Evans, Ryan Elias, Rhys Fawcett, Simon Gardiner, Dafydd Hughes, Werner Kruger, Josh Macleod, Tom Phillips, Tom Price, Lewis Rawlins.
Backs: Paul Asquith, Jonathan Evans, Ioan Hughes, Steff Hughes, Dan Jones, Johnny Mcnicholl, Ioan Nicholas, Mike Phillips, Tom Prydie, Morgan Williams.
Agence France-Presse
