Please make sure you double check with Maxis.
I did this. exactly the same method. Applied for multisim and attached the unlimited data package MR99 with the secondary card.
All my SIM card have the same number, you can make call using difference phone but using the same number.....So I used my secondary card as my Internet line (unlimited data)
But after three days, I checked my account, the amount charged by maxis was Rm2800++. I was shocked. ...
then called maxis .....then asked them why i had been charged for that amount. I did mentioned that i did subscribed for the unlimited data for the main number (which was my main line) on the secondary card...but.. I did mentioned to them that the secondary sim was used for the unlimited internet connection.
Guess??? what they said....
The unlimited data was subscribed for the main number (main sim card) and not for the second sim card (actually the second sim was using the same number too).
So, my line was barred. I cannot make any calls. Since I really want to use to line. I cancelled everything and applied for difference number and difference sim card.
The problem, I have to pay for the RM2800++, because they said I need to apply for both sim cards ...for unlimited sim.
So my case was brought up too the SKMM. I was not satisfied with MAXIS....the case was dragged me for 4 months...and finally...maxis gave back my money RM2800+++......
So, I would like to advice to anybody who is interested to do multisim..or what so ever... please double check with maxis...
The SKMM told me that my case was the 1st one.. happen last year..since that day...maxis has introduced maximum charges for pay-per-use data..
SKMM did also told me that Maxis faced abnormality in their billing system..especially if you subscribe for the multisim or what so ever...
That all...
If you want to see the letter everything..documentation made by me..sent to SKMM, Maxis etc.. private me.. this is a true story...
I just spoke to their CS about this. It seems for Multi-SIM 1 line, all you have to do is to activate RM99 unlimited data on the primary SIM card and the rest of the SIM card will enjoy unlimited data as well. So just need to pay RM99 for the service. This was not the case 2 years ago when I talked to another CS and he says RM99 unlimited data applies to 1 SIM card only. If activate on another SIM, have to pay another RM99.