The mechanism is offering an easy way for loading the URL of the provisioning server, on which the configuration files (Profiles) and / or the firmware files of the different Gigaset IP-phones are located.
Mainly the mechanism is designed for VoIP PBX’s offering an own provisioning server for the connected VoIP phones.
Before an answer is send to the initiator of the SIP-Multicast, the PBX (or SoftSwitch) has to identify the phone. This is done via the SIP-User-Agent header, which is containing at first the product name.
The SIP-Multicast mechanism is supported by most of the Gigaset VoIP phones and by the Gigaset PBX T300 and T500 (also supported by some products from other companies).
The following example flow chart shows the principle of this mechanism:
(wireshark filter"sip.Method == "SUBSCRIBE"")
Device sends Subscribe during boot:
Request-Line: SUBSCRIBE sip:MAC%3A7C2F8030D21E@local SIP/2.0
The platform answers with Notify message:
Maxwell 3 and basic software 2.11.6 wireshark trace example.