Call Setup with ICE Clients
While ICE Mobile and ICE Desktop offer soft-phone features—like a dial pad—administrators should be aware that Instant Connect does not use telephony-native protocols (like SIP) to signal or negotiate call setup. Instead, all telephony-specific protocols are terminated at the ICE Gateway server and 'converted' into ICE-native messaging and audio.
When a call is placed or received by an ICE client, the ICE client exchanges messages with ICE Server, which, in turn, exchanges messages with ICE Gateway to signal changes in call-state like 'ringing', 'busy', etc. ICE Gateway translates these ICE-proprietary messages to standard SIP messages.Once a call is established by both parties, ICE Server dynamically creates a full duplex channel configured to operate in unicast (Rallypoint) mode to carry the audio of the channel.While the user experience is quite different from push-to-talk on a channel, the ICE clients are using the same ICE media engine to convey audio between the ICE Desktop or ICE Mobile application to the ICE Gateway server. Just as ICE Gateway 'translates' signaling, it does the same for audio; the audio received over the full-duplex ICE channel is mixed and transcoded into whatever media format was negotiated with the call manager.