Symbio's IP voice network is directly interconnected with all Australia's major telecommunications carriers and is used by more than 200 service providers.
"We've built a reputation for making communications faster, simpler and smarter. NextDC's national footprint gives us coverage diversity into the future and provides flexibility in how customers can connect to us," said chief operating officer Jon Cleaver.
"The option of direct cross-connect via NextDC is an inexpensive way to do business with us while maintaining the reliability and quality we are known for."
Symbio is part of the MNF Group, which is best known for its VoIP brands MyNetFone and PennyTel.
As previously reported, the group has recently upgraded its PoPs in London and Los Angeles, and expects its new Hong Kong PoP to be "fully operational very shortly".