NocTel uses the following ports and they may need to be open on your router/firewall or not blocked by your ISP.
Used for NTP to sync device time
Used for SIP to initiate calls
Used for RTP for voice data receipt and transmission
Used for device firmware
Used for secure handset remote configuration
|All UDP Ports||UDP||Used for RTP for voice data receipt and transmission|
F: Has your ISP made a change to your modem, gateway or service?