This may happen when none of the codecs enabled in Acrobits Softphone and Groundwire are supported by your SIP or VoIP provider. Enable all the codecs in Settings > Accounts > Advanced Settings > Codecs for Wi-Fi or Codecs for Mobile Data.
Troubleshoot this issue with the following steps:
- Open the desired SIP account.
- Android - Select > Settings > Accounts.
- iOS - Open the Keypad tab, select > Accounts or SIP Accounts.
- Select Advanced Settings.
- Select Codecs for Wi-Fi or Codecs for Mobile Data, depending on the one you are using.
- Enable all codecs.
- Select or Done to save the setting.