Got.

Yoodo bro, under rm3 per month. Subscribe for their lowest sms package

yoodo free SIM , min topup rm3 to buy 50sms. i buy this everytime i need a new number

onexox prepaid
RM10 sim kad + RM30 mandatpry welcom = 36 month sim kad validity
https://xox.com.my/faq/details/onexox-plan-faq

why u need 20 sim cards ?

Avoid MVNOs if MSOS/OTP/TAC code is the main purpose...

rm3 is for 50SMS validity per month, if not mistaken the SIM card can be active for 3 month after each purchase. So will be RM3 for 4months.

yes, i also use to receive OTP , but usually before termination they will email to u so i just reload that time

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 .

it will auto deduct from card
for bank mule acc ? 

Just reload some amount of money into the app's wallet and it will auto deduct monthly

upon sign up with yoodo, you can tie up the number with your credit card to perform auto reload . I did not top up my yoodo for years. it's just auto renew my plan monthly. u can get free 7gb data with referral code. wolnm5408

hotlink pantas cost like rm30 for 1 year validity. around rm2.5 per month.
its not mvno so its reliable to receive otp.

its a virtual telco ..so everything do within the app itself, i have 2 numbers managed in the app..but never tried above that, not sure whats the limit, but do not make auto reload/subscribe or else it would deduct every month

u can choose e-sim which can work immediately, or physical SIM that is free delivery get within 3days

shouldnt have issue , have been using for few years

Why do you need 20sims?

Scalpers in the making .... LOL ...

if you do business, you can consider this instead

https://soyacincau.com/2022/12/20/tng-sound...ent-qr-ewallet/

Jangan terbeli yg fake 4090 udah lerr... banyak case kat luar sana dah ....

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

Just FYI, banks are going to phase out OTP SMS.
Just like Maybank forcing users to migrate to Secure 2U and RHB with their RHB mobile app.
And if you are going overseas you're better off with Maybank and their app. cause they allow overseas IP address whatsoever.