General networking guidelines

There are two main areas of concern when setting up your IT for good voice quality on Cradle: your computer or mobile, and your network. For advice on computer and headset setup, see our article on headset selection. Read on to make sure your network is set up correctly.

Individual computer setup

First, ensure you're using a computer with at least 8 GB of RAM, a modern processor (i5 or equivalent) that can handle the applications you're running, some free hard drive space, and a firewall setup that you understand. If your network is set up with a firewall, you probably don't need one on your laptop (or it may be managed by your domain).

We recommend that you always use a hard-wired ethernet connection. WiFi introduces jitter (more correctly, packet delay variation), where internet packets arrive out of order. Past a certain threshold this causes voice quality issues. WiFi can also get locally congested and result in dropped packets. You'll hear both as a digital, glitchy voice, or in worse cases as a total loss of voice.

Network setup

1. If your router includes SIP Application Level Gateway (ALG) function or Stateful Packet Inspection (SPI), disable both of these functions.
2. Ensure that your network respects DSCP headers. Cradle voice packets are sent with a DSCP header tag of 46 (expedited) and should take highest priority across your network. Please read this if you're using Windows to ensure DSCP headers are respected.
3. Avoid bufferbloat. This can be caused by a particular router Quality of Service (QoS) implementation or by vendor defaults. We recommend ensuring your router is configured with a low buffer size. You can test this at dslreports.com/speedtest.
4. Bandwidth minimums. Allow 50 kbits/s for each concurrent phone call you intend to make. Test your internet connection to ensure this minimum. You may need to set up QoS on your network to ensure VoIP always has a minimum of 110 kbits/s per call, otherwise large downloads or similar heavy network events could interrupt your calls. Start by reading through our basic setup page.
5. Whitelist the required domains and IP ranges below so traffic can pass through your firewall.

If you have to be on WiFi

1. Ensure you have the correct number of WiFi Access Points for the number of devices connecting to them and the size of your building. Not too many. Not too few.
2. Set the power on each Access Point so devices only connect to one AP (and see weak signals from one or two others).
3. Make both 2.4 GHz and 5 GHz available so devices can spread across both bands (this should reduce congestion on 2.4 GHz, which is typically very congested).
4. Turn off WiFi on devices that are connected via Ethernet.
5. For more depth on this topic, see this blog post.

Required limits

Jitter < 30 ms Round Trip Time < 150 ms Bandwidth > 500 kbits/s minimum plus 50 kbits/s per call Packet Loss < 2%

If you'd like more advice, please get in touch with us. We can analyse calls and help pinpoint where issues may be creeping in.

Whitelist for Cradle voice traffic

If you can whitelist IP address ranges to send UDP traffic to your machines, whitelist this range on your network:

168.86.128.0/18

The server-side port used for RTP will be between 10,000 and 60,000, and the client-side port will be between 1,024 and 65,535.

Signalling and call setup

Whitelist TCP traffic on port 443 to the following addresses. These are the call-signalling endpoints used by Cradle's voice service.

• chunderm.gll.twilio.com
• eventgw.twilio.com

Additional domains to whitelist

The Cradle desktop app and admin portal also reach out to a small set of supporting services. Whitelist the following domains (including subdomains).

• *.cradle.io Cradle's own domain. Covers the marketing site, help centre (www.cradle.io), and admin portal (admin.cradle.io).
• *.cradlekiwi.com Cradle's API and supporting services.
• *.twilio.com and *.twiliocdn.com Used to deliver voice traffic and supporting audio files (for example DTMF tones).
• *.jabra.com Used so the Cradle desktop app can integrate with Jabra headsets where they're present.
• *.googleapis.com Used for real-time data such as presence and call-log updates. If your computer can't reach this domain, Cradle won't work.
• *.lr-ingest.io Used to capture diagnostic data so we can debug specific issues.