The IP address. VOIP is via the internet, the call when it hits the SIP hardware has to have IP addresses to point to where it is going and where “to return” IP details like any communications over the internet just like when you access your bank account via the internet or the Woolies website.
The VOIP providers can be required before they allocate a number to a user to ensure that the user is Australian based or has an Australian linkage eg BHP may have a contact number that is Australian but routes to a UK base.
If someone fakes a number the IP will still show that the call originated from some locale and if outside Australia they can block it or they can mark it as non Australian/faked.
As I said currently there is no restriction on who uses Australian numbers so whether faked or not no action is taken. We happily sell the numbers to all and sundry at the moment so we don’t care about the faked ones.
Germany has the policy of requiring proof of residency or direct links eg a business connection. We don’t! Germany is not the only Country with this type of requirement but I’m most familiar with Germany’s rules on this.
One VOIP number provider of Australian numbers has this to say
" We provide real-world phone numbers directly connected to your VoIP phone (VoIP numbers are sometimes called virtual phone numbers). This means you can have Melbourne phone number allocated with your account, the number could be (03) 1234 5678. When this number is dialled from any other phone in Australia or over the world, your VoIP phone will ring and you will receive the call. A DID Number doesn’t need to reside in your location. Therefore, you may have a number that is outside your area, which means customers or family and friends can call you at local call rates if they are situated within the locality of your number. Customers can have multiple DID’s for different locations on an account.
Standard and Unlimited plans include one phone number (excluding International DID, 1300 or 1800). Please order a phone number from this page, once you have an account with us. There are no connection fees, monthly fees for the first number that are included in Standard and Unlimited plans. Any additional DID number costs $2.5 per month . You can buy an unlimited quantity of numbers per account (my bolding). Provisioning for a new number takes a few business hours, excluding numbers marked as Backorder . Backorder numbers are connected within 1-3 business days.
German Local Number requirements for VOIP and please note the 3rd point re address (this same German based detail is required for their Toll Free and National numbers)
" * Germany Local
- Name, business name and contact phone.
- Passport or ID copy*.
- Current address in Germany, must be from the same city in Germany as the DID ordered (street, building number, postal code, city).
- Proof of address (a copy of utility bill no older than of 6 months).
- Specific registration form is provided during registration process which has to be filled in and signed by the customer.
*In case registration process is performed under a company name, German company registration certificate shall be provided instead of passport or ID copy. ** Only scanned documents are acceptable for German number registration."
Nothing is foolproof but the above steps if implemented go a very long way to limiting the problem. Money incoming to the Govt is the barrier to implementation.