Sangoma has implemented SIP Authentication which includes protective measures to prevent an active attacker from modifying and replaying SIP requests and responses.
SIP authentication enables the Sangoma platform to provide its own credentials (login/password based scheme) to other gateways. It ensures that only valid users can make calls through the Sangoma platform.
The cryptographic measures are used to ensure the authenticity of the SIP message and authenticate the originator of the message as being the IMG. SIP extends the HTTP WWW Authenticate and Authorization header field and their Proxy- counterparts to include cryptographically strong signatures.