For those who bought Digi prepaid plan for usage in Malaysia, if you wish to preserve the phone number for future use when visiting Malaysia, it is best to get Digi Super Long Life that allows the number to be active for 365 days at the cost of RM 30.
To do this, you will have to change your Call plan to Digi Best Prepaid v4 plan. To do this, dial *128#
You will be given a list of options:
Digi Menu
0 Internet Subscription Packages
1 My Account
2 Super Deals
3 Internet
4 Music
5 Promotion
etc....
Key in 1 and ok, you will be brought to My Account
My Account
1 Balance
2 Reload
3 DG Savers
4 Call Plan
etc....
Key in 4 and ok, and you be shown
Call Plan: Digi Best Prepaid v3 (for example)
In order to change the plan to Digi Best Prepaid v4, you will need to dial *128*1# to change the Call Plan from Digi Best Prepaid v3 (or other plans) to Best Prepaid v4. A cost of RM3 will be deducted from your account. When confirmed, you will be able to change the validity of your plan from months to a year by dialing *128*1*7*3# (which is a short cut to opt for Super Long Life). Alternatively, you can key in step by step to get to the Super Long Life option.
Hope this helped.
If you allow your number to be inactive for a period of time, that number will be RECYCLED, unless you protected that number by added cost. I am not familiar with the plan nowadays.