ZyXEL Communications 802.11g Wireless ADSL2+ 4-port VoIP IAD P-2602HWNLI - Manual (Page 179)

P-2602HWNLI User’s Guide
Chapter 11 Voice 179
Note: When the ZyXEL Device does not have power, only the phone connected to the
PHONE 1 port can be used for making calls. Ensure you know which phone
this is, so that in case of emergency you can make outgoing calls.
You can also use the PSTN Line screen to specify phone numbers that should always use the
regular phone service (without having to dial a prefix number). Do this for emergency
numbers (like those for contacting police, fire or emergency medical services).
11.13 ISDN Line
With ISDN line you can make and receive regular ISDN phone calls. Use a prefix number to
make a regular call.
You can also use the ISDN Line screen to specify phone numbers that should always use the
regular phone service (without having to dial a prefix number). Do this for emergency
numbers (like those for contacting police, fire or emergency medical services).
11.13.1 Voice Activity Detection/Silence Suppression
Voice Activity Detection (VAD) detects whether or not speech is present. This lets the ZyXEL
Device reduce the bandwidth that a call uses by not transmitting “silent packets” when you are
not speaking.
11.13.2 Comfort Noise Generation
When using VAD, the ZyXEL Device generates comfort noise when the other party is not
speaking. The comfort noise lets you know that the line is still connected as total silence could
easily be mistaken for a lost connection.
11.13.3 Echo Cancellation
G.168 is an ITU-T standard for eliminating the echo caused by the sound of your voice
reverberating in the telephone receiver while you talk.
11.14 Analog Phone Screen
Use this screen to control which SIP accounts and PSTN line each phone uses. To access this
screen, click VoIP > Phone > Analog Phone.