All Tariff tables in all TIM products can be accessed and edited through their web interface.
Yes, all TIM products allow you to add a fixed or percentage mark-up to billing reports.
We supply a generic tariff for most countries. This would be applied at site level to ensure calls for each location recognise local dial codes and bill in the correct currency.
Yes, you can apply different tariffs to individual clients. There are no limits to the number of tariff tables allowed. You can create a completely bespoke tariff for any client or you can just edit an existing tariff and apply a new name.
Yes, as all tariffs are completely customisable, you could zero-rate calls to a specific number or destination. By saving this edited tariff under a new name, you could then apply to certain clients only.