Huawei B2368 User Manual page 137

LTE CPE B2368
User Guide
Figure 15-10 SIP Call Progression
Step 1 A sends a SIP INVITE request to B. This message is an invitation for B to participate in a SIP
telephone call.
Step 2 B sends a response indicating that the telephone is ringing.
Step 3 B sends an OK response after the call is answered.
Step 4 A then sends an ACK message to acknowledge that B has answered the call.
Step 5 Now A and B exchange voice media (talk).
Step 6 After talking, A hangs up and sends a BYE request.
Step 7 B replies with an OK response confirming receipt of the BYE request and the call is
terminated.
----End
Voice Coding
A codec (coder/decoder) codes analog voice signals into digital signals and decodes the
digital signals back into analog voice signals. The LTE Device supports the following codecs.
l
l
l
MWI (Message Waiting Indication)
Enable Message Waiting Indication (MWI) enables your phone to give you a message-waiting
(beeping) dial tone when you have a voice message(s). Your VoIP service provider must have
a messaging system that sends message waiting status SIP packets as defined in RFC 3842.
Issue 03 (2019-01-31)
G.711 is a Pulse Code Modulation (PCM) waveform codec. PCM measures analog
signal amplitudes at regular time intervals and converts them into digital samples. G.711
provides very good sound quality but requires 64 kbps of bandwidth.
G.726 is an Adaptive Differential PCM (ADPCM) waveform codec that uses a lower
bitrate than standard PCM conversion. ADPCM converts analog audio into digital
signals based on the difference between each audio sample and a prediction based on
previous samples. The more similar the audio sample is to the prediction, the less space
needed to describe it. G.726 operates at 16, 24, 32 or 40 kbps.
G.729 is an Analysis-by-Synthesis (AbS) hybrid waveform codec that uses a filter based
on information about how the human vocal tract produces sounds. G.729 provides good
sound quality and reduces the required bandwidth to 8 kbps.
Copyright © Huawei Technologies Co., Ltd.
15 VoIP
129