Call Drop outs (30s+)

Overview

This article aims to assist in troubleshooting dropped calls after the 30s mark. This article will cover the most common causes of call drops, or severely degraded call quality.

Top 4 causes of dropped calls:

1. NAT or CGNAT routing issues
   CGNAT (Carrier Grade Network Address Translation) is a form of network management for IPV4 (numbers only IP Address) networks. CGNAT maximizes potential IPV4 addresses to allow everyone internet access but can cause routing issues for SIP Packets.
   
   To avoid CGNAT interruptions, we recommend using TCP (as it is more reliable than UDP), and port 25160 (an alternate VoIP port that prevents VoIP traffic being consumed by other ISPs (cough, Telstra, cough)) when configuring Crazytel SIP Trunks with devices. The Crazyphone application uses these settings by default.
   
   
2. Bandwidth issues
   VoIP, like all streamed internet services, requires a minimum network speed for stability. Unlike most streamed services, VoIP requires very little bandwidth (network speed).
   As Crazytel uses the G.711a Codec, only 80kbps is required for stable calls.
   You can check your internet speed using the free online speed test tool: Ookla Speed Test. Both upload and download speeds should be stable with low jitter.
   
   
3. Network stability/packet loss
   Lost packets result in lost information - lost information can result in dropped calls!
   Tracking network stability can be difficult, though there are some common signs:
    - Delays in loading web pages
    - Stuttering in video streaming
    - Frequent 'No Internet' warnings on your device(s)
   
   For an easy at-home test, open your preferred Terminal (CMD Prompt on Windows, or Terminal on MacOS) and run the following code:
   ping -c 100 sip.crazytel.net.au (for MacOS)
   ping -n 100 sip.crazytel.net.au (for windows)
   
   This code will run 100 connection attempts to Crazytel's main VoIP server for 1-2 minutes. When the command completes, the average information will be displayed similar to the below:
   
   
   For optimal VoIP call quality, packet loss should ideally be below 2%. Exceeding this threshold can lead to audio distortions. If packet loss surpasses 5%, it significantly increases the risk of call drops.
   
   
4. Firewall configuration issues (Advanced users)
   As Crazytel uses a geo-redundant network, we use multiple IP addresses for call routing (some 50 odd!) If network firewalls aren't configured to allow connections from these IP addresses, there may be issues with calls.
   
   If you're a residential user, chances are your network device(s) will automatically allow connections to these addresses.
   
   If you're a commercial customer, contact your IT department and request they whitelist the IP addresses found under Account Settings in the Customer Portal.

If you're still having connectivity issues or constant call drop-outs, please don't hesitate to contact our support team.