Overview

OverSIP is a SIP proxy & server built on top of Ruby EventMachine-LE async library which follows the Reactor Design Pattern.

The SIP stack of OverSIP has been tested in several environments and interoperability with other (nice) SIP devices is guaranteed.

Features

• Fully asynchronous event-based design, but also allows synchronous style coding thanks to Ruby Fibers!.
• SIP over UDP, TCP, TLS and WebSocket transports.
• Full support for IPv4, IPv6 and DNS resolution (NAPTR, SRV, A, AAAA).
• Fully programmable using Ruby language.
• The perfect Outbound Edge Proxy.

Events and Callbacks

OverSIP provides user-programmable callbacks for different kinds of events. Those callbacks are custom Ruby code written by the user. Examples of OverSIP events are:

• SIP request/response received.
• Error sending a SIP request.
• WebSocket connection/disconnection.
• SIP or WebSocket inbound/outbound TLS connection.
• OverSIP starts/terminates.
• OverSIP is reloaded.

SIP Standards

OverSIP implements the following SIP specifications:

• RFC 3261 “SIP: Session Initiation Protocol”
• RFC 3263 “Locating SIP Servers”
• RFC 3326 “The Reason Header Field”
• RFC 3327 “Extension Header Field for Registering Non-Adjacent Contacts” (Path header)
• RFC 3581 “An Extension for Symmetric Response Routing” (rport parameter)
• RFC 4320 “Actions Addressing Identified Issues with the Non-INVITE Transaction”
• RFC 5393 “Addressing an Amplification Vulnerability in Forking Proxies”
• RFC 5626 “Managing Client-Initiated Connections” (Outbound mechanism)
• RFC 5630 “The Use of the SIPS URI Scheme”
• RFC 5922 “Domain Certificates in SIP”
• RFC 5954 “Essential Correction for IPv6 ABNF and URI Comparison in RFC 3261”
• RFC 6026 “Correct Transaction Handling for 2xx Responses to INVITE Requests”
• RFC 6228 “SIP Response Code for Indication of Terminated Dialog” (response 199)
• RFC 7118 “The WebSocket Protocol as a Transport for SIP”

Not (Yet) Implemented or Planned

Due to the nature and purpose of OverSIP, the following SIP features are not implemented:

• HTTP/SIP Authentication.
• Registration.
• Parallel forking.