Not clear what the question is.
Sipbroker can be accessed from providers that support peering to other networks via the Sipbroker service.
If your ATA or softphone is registered with Voxalot, then from your Voxalot account, you dial [*Code & Account_Number].
The *Code is listed for all providers on the Sipbroker page :
SIPBroker - Provider White Pages
The account number is the number associated with the SIP account you are trying to establish a call with.
You can also reach the Sipbroker service using a PSTN access number:
SIPBroker - PSTN Numbers
Regards ........