their is two ways to do that but for both way you need to call Voda customer car
1. Call customer care and then ask for Call barring password and then block it from your mobile..(I believe everytime you change mobile you have to do this).. Never done this myself.
2. Block calls on your number itself so what ever phone you use. calls won't be possible..
IMO get Barring password do it your self so you have control so you can unlock it anytime you need without contacting Custome care..