VIA provides functionality to change the way end-users have to dial numbers for the result to "normalise" for external calling.
For example, a normalised number in the UK would be +443333442464 however, the user may dial 03333442464 or +44(0)3333442464 to reach to same destination.
VIA provide localisation for dialling in the UK, Australia and USA.
To change the "Dial Plan" assigned to a particular user, navigate to the VIA Portal, select the user and then change the "Region" to the desired localised Dial Plan.
Europe - UK (+44)
Australasia - Australia (+61)
North America - USA (+1)
Any changes may take up to 4 hours to replicate in Office 365. Please be patient. The end-user will have to sign out in order for the changes to take effect.