User's Manual

Chapter 15 VoIP
B222s User’s Guide
122
SIP
SI P st ands for Session I nitiat ion Prot ocol. SI P is a signalling standard that let s one network device
( like a com puter or the LTE Device) send m essages to anot her. I n VoI P, t hese m essages are about
phone calls over t he net work. For exam ple, when you dial a num ber on your LTE Device, it sends a
SI P m essage over t he net work asking the ot her device ( the num ber you dialed) t o t ake part in t he
call.
SIP Accounts
A SI P account is a type of VoI P account . I t is an arrangem ent wit h a service provider t hat let s you
m ake phone calls over t he I nternet . When you set the LTE Device t o use your SI P account t o m ake
calls, t he LTE Device is able t o send all the inform ation about t he phone call t o your service prov ider
on t he I nternet .
St r ictly speaking, you don’t need a SI P account . I t is possible for one SI P device ( like the LTE
Device) t o call anot her without involving a SI P service provider. However, t he net w orking difficult ies
involved in doing t his m ake it t rem endously im practical under norm al circum stances. Your SI P
account provider rem oves these difficulties by taking care of t he call rout ing and set up - figuring
out how to get your call t o the right place in a way that you and t he ot her person can t alk t o one
anot her.
Voice Activity Detection/Silence Suppression
Voice Activit y Det ection ( VAD) det ects whether or not speech is present . This let s the LTE Device
reduce t he bandwidt h t hat a call uses by not t ransm itt ing “ silent packet s” when you are not
speaking.
Comfort Noise Generation
When using VAD, the LTE Device generat es com fort noise when t he ot her part y is not speaking. The
com fort noise let s you know t hat t he line is still connected as t otal silence could easily be m ist aken
for a lost connect ion.
Echo Cancellation
G.168 is an I TU-T st andard for elim inat ing t he echo caused by the sound of your voice
reverberating in the telephone receiver while you t alk.
Use t his screen to m aint ain basic infor m ation about each SI P account . You can also enable and
disable each SI P account , configure t he volum e, echo cancellat ion and VAD ( Voice Act ivit y
Det ection) settings for each individual phone port on t he LTE Device.
How to Find Out More
See
Chapter 3 on page 33 for a t ut orial showing how to set up t hese screens in an exam ple
scenario.
See
Section on page 135 for advanced t echnical inform at ion on SI P.