To prevent the Grandstream ATA's (or phones) to hangup after exactly 17:28 minutes change the settings below:
VoipNow:
Provisioning - Allow re-invites from this extension : ON
Grandstream device:
UAC Specify refresher: UAS
UAS Specify refresher: UAS
Force INVITE: Yes
Login to the ATA through the LAN port.
IP is 192.168.2.1
Default password: admin
