Below you will find the protocols used by hardware delivered by Telavox together with a description of their functions. Different types of terminals use different protocols. As an example, HTTPS is preferred for retrieval of software instead of TFTP and HTTP. In cases where the terminal does not support HTTPS, one of the other is used. Telavox does not recommend that you block traffic to and from terminals based on ports and/or protocols, we instead recommend that you trust all traffic to and from the Telavox network. Telavox does not pledge to only use the protocols below. Please observe that the specified ports are receiving ports, as a rule rather than an exception, our hardware uses randomly chosen sending ports.
Domain Name Server, RFC1035, TCP/UDP port 53. DNS functionality is a part of a working IT network and the terminals delivered by Telavox don’t work if they don’t have access to a working DNS. In the case where the DNS is placed outside the firewall, the firewall must allow the terminals to suggest the DNS. Our provisioned phones are configured with Googles DNS:s 126.96.36.199 and 188.8.131.52.
Hyper Text Transfer Protocol, RFC2616, TCP port 80. Used to retrieve terminal configuration and software. Normally, no special configuration is required for HTTP to work well.
Hyper Text Transfer Protocol over Secure Socket Layer, RFC2818, TCP port 443. Used Used to retrieve terminal configuration and software.
Trivial File Transfer Protocol, RFC1350, UDP port 69 and dynimically allocated ports for data transfer. Used to retrieve terminal configuration and software.
(Simple) Network Time Protocol, RFC1305/RFC1361, UDP port 123. Used to set the date/time in the terminal.
Session Initiation Protocol, RFC3261, UDP port 5060. Used to connect and disconnect calls. The SIP-traffic runs between our SIP-servers and the phone. This is the most important protocol for the phone service to work.
The picture below show the SIP-traffic between two phones.
Real Time Transfer Protocol, RFC1889, UDP port 1024-65535 (Telavox uses UDP port 10 000-20 00) The sound during a conversation runs via RTP. The port used for the call is randomized when the call is initiated. All of Telavox delievered terminals use symmetrical RPT which means that the recieving and sending port for the RTP-stream are the same for both outgoing and incoming sound. This means that the soundstream that goes from the terminal to us opens up a session in the firewall to allow even incoming soundstreams over the same session.
Real Time Control Protocol, RFC3550, UDP port 1024-65535. Some terminals generate RTCP-packets used in the communication between RTP-endpoints to convey local statistics and conversation data aswell as information about jitter and eventual packetloss.