Prerequisites:

Access to the portal with Office Manager or greater credentials. 

 

This article is a troubleshooting reference for Grandstream Analog Telephone Adapters (ATAs), covering device registration, audio connectivity, and diagnostic strategies for HT8xx series models.

Troubleshooting Grandstream Analog Telephone Adapters (ATAs) can be complex, but you can quickly resolve most connectivity and performance issues with the right approach. This guide will walk you through systematic diagnostic steps for the HT8xx series models, helping you restore your voice communication systems efficiently.

Supported ATA Models

  • HT801: Single FXS port
  • HT812: Two FXS ports with WAN/LAN connectivity
  • HT813: One FXS and one FXO port
  • HT818: Eight FXS ports

Pre-Troubleshooting Checklist

Before diving into complex diagnostics, confirm these fundamental elements:

  1. Power LED is steady and illuminated
  2. Ethernet cable connected to the WAN port
  3. Analog phone connected to the FXS port
  4. SIP account is correctly provisioned
  5. Firmware is current
Setting Recommendation
SIP Server yourpbx.domain.com
Transport UDP
Codecs G.711u / G.711a
Registration Timeout 60
Dial Plan x+
NAT Traversal Keep-Alive

PBX Portal Tips:

  • Under User > SIP Settings, confirm the registration limit and transport match device.
  • Disable unused codecs to reduce negotiation errors.

Device Testing & Voice Menu Access

  1. Pick up the analog phone → Dial ***
  2. Use the following options:
    • 02 – Play IP address
    • 12 – Reboot the device
  3. Enable Syslog and SIP Debug for detailed support.

Common Troubleshooting Scenarios

Issue Likely Cause Fix
Not Registered Incorrect SIP settings or blocked ports Check SIP Server, Auth ID, NAT settings
No Audio NAT/SIP ALG issues Disable SIP ALG, check RTP ports
Fast Busy Dial plan or PBX restriction Use x+, review answering rules
Call Drops NAT or Keep Alive issues Set static IP, adjust keep-alive settings

Device Not Registering

Symptoms: No dial tone, fast busy, "Not Registered" status

Recommended Actions:

  • Verify SIP server settings
  • Check authentication credentials
  • Ensure the firewall permits ATA traffic

Steps to Resolve:

  1. Access the ATA Web UI via IP (e.g., http://192.168.1.100)
  2. Login (default is admin / admin or admin / device MAC)
  3. Go to FXS Port Settings and confirm:
    • SIP Server = yourpbx.yourdomain.com
    • SIP User ID, Auth ID, Password = from the Portal
    • Register = Yes
    • SIP Transport = UDP
  4. Click Apply and Reboot.

Audio Connectivity Problems

Symptoms: One-way audio or no audio during calls

Recommended Actions:

  • Disable SIP ALG on the router
  • Enable NAT traversal
  • Open RTP port range (10000-20000 UDP)

Steps to Resolve:

  1. Disable SIP ALG on router/firewall.
  2. Set NAT Traversal to Keep-Alive in ATA.
  3. Open the UDP port range 10000–20000 on the firewall.
  4. Ensure that the correct public IP or media relay is configured.
  5. Use STUN if Keep-Alive doesn't resolve NAT issues.

Fast Busy - Calling Restrictions

Symptoms: Fast busy tone, inability to dial out

Recommended Actions:

  • Review dial plan configuration
  • Verify line activation status
  • Check portal-level call restrictions

Steps to Resolve:

  1. Check if the dial plan is correctly configured. Example: x+ (allows any number).
  2. Ensure Line Active is set to Yes under FXS Port Settings.
  3. Verify that no call restrictions are set for the user in the portal.
  4. Test with another number to rule out carrier issues.

Dropped Calls or Unreliable Behaviour

Symptoms: Random call drops, audio stutters, or poor performance.

Steps to Resolve:

  1. Set a Static IP or use a DHCP reservation.
  2. Disable SIP ALG and double NAT on the router.
  3. Adjust:
    • Registration Timeout = 60
    • Keep Alive Interval = 20–30
  4. Update the ATA to the latest firmware version.

Diagnostic Quick Reference

Recommended Setting Value
SIP Transport UDP
NAT Traversal Keep-Alive
Registration Timeout 60 seconds
Recommended Codecs G.711u / G.711a

Final Resort: Factory Reset

If all troubleshooting steps fail, perform a factory reset by:

  • Press the reset button for 7-10 seconds (watch for the LED to blink).
  • Using web UI: Maintenance → Factory Reset
  • Warning: Factory reset erases all custom settings. Back up first!

When to Escalate

If none of the above steps resolve the issue:

  • Confirm with your ISP that there are no port restrictions or SIP blocking.
  • Test on another device or in another location to isolate the problem.

Collect the following before contacting support:

  • Device Model + Firmware Version
  • SIP logs 
  • Screenshots of the ATA configuration
  • Time & Date of failed attempts