sim card active 3 month maybe is a wrong info , after each purchase , the sim active for 1month , then passive 2month , before it terminate . so each purchase total can hold for 3month .

so you need 10 x dual sim phone to received sms , 1 telco type can register up to 5 sims , so you need find 4 type of telco plan .
or using other id register for 1 type x4 person .

if you got time to play around those telco plan (mean need using low $ ) , choose :
1. yoodo rm3 sms plan about 3 month purchase once (around rm12/year)
2. umobile prepaid rm1 buy 1day validation about each 2month . (around rm5/year)
3. hotlink pantas topup rm10 for about each 2month after have rm30 then buy 365days pass . (rm30 for 1.5year)

my umobile line is doing this way now , not use for call or data , just to received call or sms , so i just buy the rm1 validation to extend for 2month , if out of credit just topup . the umobile will send sms 7 days before terminate for remind . myself have record in a note , so can monitor the date .
so 1year spend less then rm10