15.6.2 SIP
The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol that
handles the setting up, altering and tearing down of voice and multimedia sessions over the
Internet.
SIP signaling is separate from the media for which it handles sessions. The media that is
exchanged during the session can use a different path from that of the signaling. SIP handles
telephone calls and can interface with traditional circuit-switched telephone networks.
SIP Identities
A SIP account uses an identity (sometimes referred to as a SIP address). A complete SIP
identity is called a SIP URI (Uniform Resource Identifier). A SIP account's URI identifies the
SIP account in a way similar to the way an e-mail address identifies an e-mail account. The
format of a SIP identity is SIP-Number@SIP-Service-Domain.
SIP Number
The SIP number is the part of the SIP URI that comes before the "@" symbol. A SIP number
can use letters like in an e-mail address ([email protected] for example) or numbers
like a telephone number ([email protected] for example).
SIP Service Domain
The SIP service domain of the VoIP service provider is the domain name in a SIP URI. For
example, if the SIP address is [email protected], then "VoIP-provider.com" is
the SIP service domain.
SIP Registration
Each LTE Device is an individual SIP User Agent (UA). To provide voice service, it has a
public IP address for SIP and RTP protocols to communicate with other servers.
A SIP user agent has to register with the SIP registrar and must provide information about the
users it represents, as well as its current IP address (for the routing of incoming SIP requests).
After successful registration, the SIP server knows that the users (identified by their dedicated
SIP URIs) are represented by the UA, and knows the IP address to which the SIP requests and
responses should be sent.
Registration is initiated by the User Agent Client (UAC) running in the VoIP gateway (the
LTE Device). The gateway must be configured with information letting it know where to send
the REGISTER message, as well as the relevant user and authorization data.
A SIP registration has a limited lifespan. The User Agent Client must renew its registration
within this lifespan. If it does not do so, the registration data will be deleted from the SIP
registrar's database and the connection broken.
The LTE Device attempts to register all enabled subscriber ports when it is switched on.
When you enable a subscriber port that was previously disabled, the LTE Device attempts to
register the port immediately.
LTE CPE B2368
User Guide
15 VoIP
Issue 03 (2019-01-31)
Copyright © Huawei Technologies Co., Ltd.
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