Please see below our recommended advanced settings for oneFone V1.8.
Advanced
Start on boot – Determines whether to open oneFone on the start up of handset
IAP – Use only to force a specific IAP. This is typically used to force oneFone to use a 3G IAP. You must restart oneFone after changing this setting.
Low bandwith codec – Select “No” for WLAN and “Yes” for 3G
Disable Vad – Should be left on “Yes”
Warn Billable Events – Should be left on “No”
Disable Outbound VoIP – Should be left on “No”
Fixed Jitter Buffer – Should be left on 4/16
