Australian sim card

Hi expats im a Aussie living in Saigon .to open a bank account in vietnam i have to have a vietnam phone number.my question is this if i take my Au sim our of my phone put a local sim in do i loose all my apps like Hotmail.  Viper. Skype my au internet banking etc thanks all
Also any expats need a house mate ?
Cheers all
Gwyn

Hi Gwyn Hill, it's absolutely okay if you change your sim. All of your apps are still in your phone.
Best regards,
Nhung.

Oh excellent Nhung thank you so much my friend warm regards  Gwyn

You're welcome

Everything stays on your phone, but you'll need to either change the number in your Viber account or put the Australian SIM back each time you make a call using Viber. 

I'm in the reverse situation right now, with an Australian SIM in my phone instead of my Vietnamese one.  I cannot make calls via WhatsApp unless I change the number.  It's too much hassle, so I've decided to be incommunicado for the duration of my holiday instead.