Usually Malaysia side Won't call your Singapore number. Due to overseas call rates.
But when you are overseas, you do not need to pay for answering calls.
One easy way to confirm, is to have $0 in Wallet. And try answering calls.
If you are able to make/answer calls in SG without VOICE APP. You can carry on to do so while overseas.
SIMBA TPG - ROAMING VOICE CALLS AND SMS
Ok. Emailed SIMBA TPG regarding voice calls.
They support
up to 124 destinations for Roaming (and data roaming).
As long you have
VoLTE coverage over there, you
Do Not Need to have Data Roaming to have Voice Calls and SMS.
Voice Calls (Incoming)::
1. All voice calls are
FREE
Voice Calls (Outgoing)::
1. Calls to SG Mobile -
FREE
2. Calls to Fixed Line - Deduct from Bundle
3. Calls to IDD (1 or 21 Countries) - Deduct from IDD Bundle or Pay As You Use (Main Wallet)
IDD::
$18 SIM-Only130 :: 300 Mins
$25 SuperRoamMax :: 300 Mins
$20 SuperRoam50GB :: 300 Mins
$30/90Days* ($39/90Days)
SuperRoamMY :: 100 Mins (MY only)
SMS (Incoming) :: FREE
SMS (Outgoing) :: Not Available
Data Roaming::
1. Free for Up To 57 destinations (Group A)
2. Deduct from Main Wallet (10mb block)