SIP Proxy

A SIP proxy is used with Asterisk for two main functions:

 To assist with NAT traversal and to load balance across across multiple telephony servers to build an Asterisk system that can scale to thousands of concurrent calls, handling hundreds of calls per second.

 A SIP proxy is also used as part of a larger redundant deployment of Asterisk to send calls to only operational telephony servers.

SIP Proxy in front of A2Billing



VoIP Wholesale

Use a SIP proxy for high capacity wholesale VoIP systems

Calling Card

Run massive calling card operations with a SIP proxy in front of A2Billing

Residential VoIP

Use a SIP proxy for reliable NAT traversal for residential customers


A SIP proxy can be part of a larger redundant system

Core Features

  • High Capacity by load balancing across multiple servers
  • NAT traversal especially for residential VoIP customers
  • Redundancy by routing calls to working telephone servers only.
  • Zero configuration when integrated with Asterisk Realtime.
  • Topology hiding to present a smaller attack surface area.

Products to consider

The A2Billing Enterprise Switch is a full featured calling card, VoIP, DID resale and call-back platform with inline billing.

A SIP proxy can be applied to the front of any existing or new A2Billing system, and it is included as standard on our enterprise multi-server system.

Click to find out more about The Enterprise A2Billing Switch and to purchase installation, training and deployment support.

Click to find out more about Enterprise A2Billing Switch

Click for prices for an installation with an existing system or bespoke build

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