Simplifi Contact - No Audio from Grandstream Cordless Handset During Call

Grandstream factory enables a Vocoder Setting called OPUS that is not compatible with Simplifi Core. The OPUS Codec must be manually disabled through the web GUI of the phone.

1. Log into the Grandstream web GUI
   1. Obtain the IP address of the affected phones base station
      1. From the handset, press the center circle button
      2. Go to Status and press Select
      3. Select Base Status and note the IP Address
   2. From a computer on the same network as the phone, open a web browser and type in the IP address of the phone.  This will open the Grandstream web GUI login page.
      1. The default Login/Password are Admin/Admin
      2. Note: Some devices list a unique password on the back of the base station
2. Navigate to the Profile you wish to edit (Profile 1 in this example)
   1. Go to Audio Settings
   2. Change the Preferred Vocoders (1 thru 8) to PCMA and PCMU, alternating
      1. Note: PCMA and PCMU are the same as G711a & G711u
3. Change the “Use First Matching Vocoder in 200OK SDP" to Yes.
4. Click Save and Apply