Information Systems:Phone System Troubleshooting Checklist

Use this page as a starting point for diagnosing and troubleshooting issues related to the phone system. Issues and fixes should be added here as they are encountered, for future reference.

Troubleshooting tips

Problem	Suggested fix
Need 3CX configuration support	3CX has excellent documentation on its website, as well as a very active forum. For critical issues, RingOffice offers premium support. 3CX also offers premium support at $75 per ticket/issue.
Modify existing VoIP services	Use the ThinkTel and RingOffice web portals.
No dial tone	A dial tone indicates communication between the IP phone and 3CX (not necessarily related to SIP trunks). If there is no dial tone, the phone might not be connecting to the PBX. Check physical network connections as well as extension registration (via the phone's menu or web GUI).
3CX not accessible after firewall changes i.e. phone system seems to be down	Reboot the firewall. Caution: Rebooting the firewall reboots the firewall. Know what you're doing first.
Outside caller cannot reach an internal extension directly	Use uControl to check that the number is assigned to the main SIP trunk and not the reservation trunk. Check 3CX to see if an inbound route exists.
Headset not working	Try unplugging the headset and plugging it back in. Also try restarting the phone from the 3CX web console.
Call history inaccuracies	check to see what 3cx webclient thinks should be the Primary Phone

Notable issues

Issues past and present worth documenting for reference.

One-way audio during calls

A few weeks after going live with the new phone system and service, users reported random one-way audio drop-outs i.e. mid-call one party would suddenly be unable to hear the other.

The culprit was UDP Flood Protection, which is a firewall mechanism that protects against a flood of packets by temporarily blocking the IP if the packet rate (pps) exceeded a certain level (configurable in the web GUI). The fact that there is lower visibility into this mechanism (i.e. events log to a separate file for a module which is otherwise deactivated (Intrustion Prevention) besides these flood protection mechanisms) is a known Sophos quirk (check the community forums). The randomness would be due to a sudden block either in the transmit or receive directions of RTP audio. An exception was added to forgo UDP FP for traffic from/to the PBX.

Headset automatically picking up calls

EPOS headsets have call control functionality that allow incoming calls to be picked up using the Call Answer button on the headset. The normal behavior is for the Call Answer signal to be sent only when either the button is pressed, or the headset is taken off-hook i.e. removed from the base (on-hook). However, Customer Service agents reported that calls were at times and randomly being automatically answered (picked up) without a button-press and while off-hook (e.g. call answered while headset sitting on desk or being worn while walking down the hall).

As of May 2021, this is still being reported by some Customer Service agents. The user testimony and issue-reporting surrounding this particular problem is wildly inconsistent. It is being thoroughly investigated and this section will be updated with the outcome/fix -norwizzle (talk)