General FAQ

1. How do I access the SMG Web Gui from a remote system?
2. Why is the signal level reduced by the FXS interfaces?

 

---

 

1. How Do I access the SMG Web Gui from a remote system?
   
   ..info coming soon
2. Why is the signal level reduced by the FXS interfaces?

On A200 FXS cards, between 8.0 to 9.0 dB is loss as the signal goes through the FXS card to the analog line.  This behaviour is by design.

Scenario:  Setup call flow as below, with FXS connected to FXO back-to-back on the same card.  Once the call is connected, DTMF digits are pressed on the both SIP phones and wan_ec_client monitor is done on both FXS and FXO sides.  
 

Test 1) FXO => FXS (SIP phone 1 sends digit):  SIP Phone 1 => Softswitch => FXO => FXS => Softswitch => SIP Phone 2

  FXO signal level = -17.5 dB
  FXS signal level = -17.1 dB
  Result:  gain of 0.4 dB

Test 2) FXS => FXO (SIP phone 2 sends digit):  SIP Phone 1 <= Softswitch <= FXO <= FXS <= Softswitch <= SIP Phone 2

  FXS signal level = -17.5 dB
  FXO signal level = -25.7 dB
  Result:  loss of 8.2 dB

NOTE:  Softswitch can be Freeswitch, or Asterisk.

As you can see, in test 2, there is a 8.2 db loss going from FXS to FXO.  To compensate for the loss, a gain can be applied on the RX direction of the FXO (not FXS) line at the application level.

To apply a 6.0 dB gain on asterisk, update chan_dahdi.conf.  For example:

;Sangoma AFT-A200 [slot:0 bus:8 span:1]  <wanpipe1>
context=from-zaptel
group=0
echocancel=yes
signalling = fxs_ks
rxgain=6.0
txgain=0.0
channel => 1

To apply a gain on Freeswitch, update freetdm.conf.  For example:

#A200 FXO Ports
[span wanpipe wp3-FXO]
name => freetdm
trunk_type => fxo
group=> g11
rxgain => 6
txgain => 0
fxo-channel => 3:3

NOTE:  For both Asterisk and Freeswtich, the gain setting is entered before the channel declaration.