Enterprise & Residential System

The Enterprise & Residential System is broadly similar in architecture to the Enterprise system, except it adds a SIP proxy and RTP Proxy to assist with NAT traversal, and to load balance across multiple Asterisk Servers. It has all the benefits of a Standard A2Billing system, with the added advantage of very high capacity.

  • Far end NAT traversal, assisting SIP endpoints to connect through Network Address Translation, which is often a problem with certain types of SIP endpoint and NAT device.
  • Intelligently Load Balancing across multiple Asterisk servers to make maximum use of the resources available.


The Enterprise & Residential VoIP system comprises of the following components, generally hosted on four or more servers:-

  • 1 x Database server, which contains the A2Billing Database. This server should have good I/O and plenty of memory.
  • 1 x Web Server, which provides the Admin, Agent and Customer portals, and may also Telco’s website.
  • 1+ Asterisk servers, as many as are required to suit the desired capacity. Asterisk servers  can be added later to increase capacity.
  • 1 x SIP Proxy and RTP Proxy, which provide load balancing and NAT traversal.

The Enterprise & Residential System can provide customers will all the standard services of any A2Billing system, but is most popular for providing residential VoIP services. Voice-mail can be added to this system to provide a full featured service for your customers.

The SIP Proxy is seamlessly integrated into A2Billing, and once it has been configured by our installation team, no further configuration is required on the SIP proxy as it takes it configuration from the A2Billing database, which is in turn configured via the A2Billing Admin user interface.

The architecture chosen means that this system can be easily expanded in terms of capacity simply by adding more Asterisk servers, and telling the SIP Proxy that they exist. The SIP proxy can handle SIP registrations of many thousands of customers, and the number of concurrent calls depends on the Asterisk server hardware, call type and bandwidth.

Solutions Provided

The Enterprise and Residential System is mainly aimed at large scale residential VoIP, however, the same platform can deliver the following services as well. For smaller residential VoIP deployments, consider a Standalone Switch, and add in a Session Border Controller for NAT traversal.

  • Calling Card – A2Billing can be used to provide call-through services, such as calling card products
  • Call-back – Call-back is traditionally used where the calls to international destinations are expensive, and it is cheaper to phone into the country, and present secondary dial-tone.
  • VoIP Termination (Residential) – A2Billing can be used to terminate and bill calls from SIP and IAX endpoints.
  • VoIP Termination (IP-PBX) – With the growth of IP PBX systems, many of which are freely available, A2Billing can be used to terminate and bill these calls.
  • VoIP Termination (Wholesale) – A2Billing can be scaled to terminate many concurrent calls from other switches.
  • DID Resale and delivery platform. – A2Billing can provide DID services and forward calls onto VoIP endpoints or to PSTN destinations, with DID billing.


As with most Star2Billing products, the software is free, we simply make a charge for installation, training and consultancy. The cost of installing this system depends on the desired capacity, and how many Asterisk servers are required. Discounts can be given to those with A2Billing experience on the basis of a reduced training and support requirement.

Please contact us for recommendations and pricing.