Singtel will be using Ericsson for the core components of its networks, while StarHub and M1 have selected Nokia to supply core network and radio network access equipment.
StarHub is exploring using vendors including Nokia and Chinese vendors Huawei and ZTE for other network elements, whereas M1 is reviewing Ericsson, Nokia and Huawei.
"Our CFP process did not exclude any vendor...the emphasis was on security, resilience and performance," Mr Iswaran said, noting that Singapore's 5G networks will have good vendor diversity.
He also said that Singapore's 5G ecosystem will continue to evolve, creating "further opportunities for participation".