The OtxSIP library is a software library that implements the Session Initiation Protocol (SIP) protocol for the industry award-winning Odin Telecom frameworX (OTX) hardware. The library is based on the RFC 3261 specifications.

SIP is widely used by telephony services such as multimedia conferences and many other real-time and person-to-person communication services. It is also adopted as the signal communication protocol of VoIP and 3GPP.

The OtxSIP library has a set of functions to accomplish a wide variety of SIP related tasks. An example of such tasks include enabling internet endpoints to negotiate the character of a shared multimedia session. Other functions could create, modify or terminate a multimedia session which works independently of any underlying transport protocols.

The OtxSIP library is supported by multiple types of Odin's OTX-Plus PCI/PCIe and ExpressCard/54 adapter boards. It is also supported by the Odin's Alvis-CSI stand-alone desktop and rack-mountable family of products. The OtxSIP library runs on Win32, Linux and Davinci (ARM) systems.