How much internet speed do VoIP calls actually need?
Summary
Less than most people expect. RingCentral recommends 90 Kbps or more per voice line and Microsoft recommends 58 Kbps up and down for a Teams audio call, so ten calls at once still fit under 1 Mbps. Choppy audio on a fast connection points elsewhere: delay (latency), uneven delay (jitter), lost packets, or other traffic competing on the same line. A speed test headline number shows none of these.
The bandwidth numbers
Microsoft's network planning guide for Teams gives per-device figures in three levels. Audio needs 10 Kbps up and down at minimum, 58 Kbps recommended, and 76 Kbps for best performance, the same for one-to-one calls and meetings. One-to-one video, by comparison, is 1,500 Kbps recommended. RingCentral asks for a high-speed DSL, cable, or fiber connection with dedicated upload and download bandwidth of at least 90 Kbps for each voice line you plan to run.
Latency, jitter, and lost packets
RingCentral publishes the clearest thresholds:
- Latency of 150 ms is barely noticeable and generally acceptable. Above 150 ms, quality suffers, and above 300 ms it is generally unacceptable.
- Jitter greater than 50 ms can cause packet loss and degraded voice quality.
- Packet loss gets no number. RingCentral's example is that if you miss one out of every 10 words, or 10 words at once, you probably won't follow the conversation.
Microsoft ties the symptoms together: calls with static, cutouts, or voices that sound like robots could be jitter or packet loss.
When other traffic gets in the way
A big download or a video meeting on the same connection can crowd out voice packets. RingCentral says QoS-enabled routers prioritize voice traffic over lower-priority data such as large downloads. Microsoft recommends QoS on every segment of a managed network, notes that Teams protects audio before video when bandwidth runs short, and warns that routing calls through a VPN can add latency and jitter.
Outages are a separate problem
No amount of tuning helps when the office internet or power goes out. The FCC says VoIP may not work during a power outage or when the internet connection fails or becomes overloaded, and suggests backup power, a traditional phone line, or a wireless phone as a fallback. RingCentral's emergency services policy lists internet or power outages, suspended broadband service, and network congestion among the situations where emergency calls may not go through. Rerouting incoming calls to cell phones during an outage is covered in the article on how cloud phone systems work.
Sources
- learn.microsoft.com/en-us/microsoftteams/prepare-network
- ringcentral.com/support/qos-information.html
- fcc.gov/consumers/guides/voip-and-911-service
- ringcentral.com/legal/emergency-services.html
Related on this site
- What happens behind the scenes when someone calls a cloud phone number?
- Will 911 know where you are if you call from a VoIP phone?
- Do you still need desk phones if your business phone system has an app?
- Can you keep your business phone number when you switch providers?
- What does a year of business phone service cost for a 10-person team?
Written by Kaz (pen name). Figures are copied from providers' published pricing pages on the dates shown. We have not used these products. Corrections: contact form.