TekSIP is a freeware SIP Registrar/Proxy.

TekSIP complies with RFC 3261, RFC 3263, RFC 3311, RFC 3581 and RFC 3891. It supports NAT traversal. You can select IP address to be listened, default SIP endpoint for outgouing calls. You are also able to log session details into a log file.

Here are some key features of "TekSIP":

· Supports features described in RFC 3261 and ENUM (e164.arpa domain only).
· Logs system messages, errors and session information to a log file.
· All parameters can be configured through management GUI.
· Provides NAT traversal between registered SIP UAs.
· You can define a default SIP route for outgoing calls.
· You can redirect calls to alternate enpoint when called endpoint is off-line.
· You can monitor active registrations and SIP calls in realtime.
· Clears expired registrations automatically.
· Stores configuration data in the installation directory (.ini file).
· Quick and easy installation.

Requirements:

· 512 MBytes of RAM.
· Microsoft.NET Framework v2.0.50727 (Min.)
· 1 MByte for installation.

Limitations:

· This freeware version allows maximum 5 SIP endpoints registration and 5 simultaneous SIP sessions (Calls)