If one has been monitoring the active coverage areas of different telecommunication companies, it may have been observed that the SIMBA network can be accessed in certain parts of Johor Bahru even if the user has not enabled the free 1 GB, 10 GB, or 50 GB data roaming (depending on the chosen plan).
Furthermore, the SIMBA 4G signal is capable of reaching from JB central to Pasir Gudang, as evidenced by the purple line which signifies the coverage of 5G NSA signals along the causeway and orange line indicating 4G and red line for 4G+ coverage.
Therefore, if you find yourself in Johor Bahru, it would be worthwhile to check for the SIMBA signal along the coastal areas to utilize your 100 GB or 130 GB data plan. If you are located further north, you may consider enabling your data roaming.