Hmm, same for M1 Maxx, Starhub giga and Singtel hi postpaid and Singtel Gomo. No extra charges.
Zym/Zero1/VIVIFI/CMLink: high pay as you go roaming incoming/outgoing voice and outgoing roaming SMS charges.
SIMBA??
The following is what I have gathered. Please correct me if I miss some extra charges or I am wrong. Thanks.
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SingTel and M1 MNO plans have potential high Pay per Use roaming voice charges and roaming outgoing SMS charges. There will be extra roaming data charges as well with ReadyRoam or M1 Data Passport.
Starhub new MNO plans: no extra charges
SIMBA MNO plans: excess local data charges, high excess roaming data charges. Also got charges for excess local calls, local SMS and IDD calls.
SingTel Gomo: no extra charges
SingTel hi! Postpaid: no extra charges
Zym/Zero1/VIVIFI/CMLink: high pay as you go roaming incoming/outgoing voice and outgoing roaming SMS charges
Starhub gigia: no extra charges
Starhub eight: no extra charges
Starhub Prepaid: no extra charges
M1 Maxx: no extra charges
CL: high pay as you roam data charges, high pay as you roam roaming incoming/outgoing voice and outgoing roaming SMS charges
MR: high pay as you go roaming incoming/outgoing voice and outgoing roaming SMS charges
CUniq: high pay per use roaming data charges, high pay per use roaming incoming/outgoing voice and outgoing roaming SMS charges