Looking for a prepaid telco plan for senior citizen

they only know how to call / receive from phone , so data plan is not that important.
need to have long validity  , if possible low cost . 

Any suggestion on this ?

Go for Unifi Mobile: Budget-friendly calls, but with caveats.

Pros:

1. Cheap calls: The lowest prepaid call rate at RM20 for 200 minutes (that's just RM0.10 per minute!),
    and even better, it's charged by the second after the first block, saving you more.
2. Super long validity: Keep the prepaid line active for a whopping 89 days,
    just by making at least one outgoing call every 89 days.

Cons to consider:

1. Active call reminder: To maintain the extended validity, remember to make a call every 89 days.
Unfortunately, the Unifi Mobile app doesn't show your expiry date,
so set calendar reminders or watch for their final 80-day warning SMS.

2. Limited reload options
Due to fewer physical dealers, topping up your prepaid account might require using your bank card through the Unifi Mobile app.
Not everyone enjoys this digital-only approach.