How the calculation works
Voice. Every minute of voice on your talk group is one audio stream for your radio, up or down. Megabytes = kbit/s × seconds ÷ 8 ÷ 1,000. Rates include packet headers where the source gives them; headers matter, because a voice packet carries only 20–60 ms of sound.67
| App | Rate while audio flows | Per hour of voice | Idle, a day | Basis |
|---|---|---|---|---|
| Zello | 12–45 kbit/s | 5.4–20.2 MB | 0.48 MB | Zello’s own figure: 12 kbit/s on 2G or weak links, 45 kbit/s when both ends are on Wi-Fi; idle 20 kB an hour.1 |
| Zebra PTT Pro | 49 kbit/s | 22.1 MB | 0.67 MB | Zebra: about 22 MB per hour of talk on 4G, 5G or Wi-Fi; idle about 20 MB a month.3 |
| Microsoft Teams Walkie Talkie | 20 kbit/s | 9.0 MB | negligible | Microsoft: about 20 kbit/s when sending or receiving audio; idle use negligible.4 |
| GroupTalk | 42 kbit/s | 18.9 MB | 0.5 MB | GroupTalk: 1 MB covers about 50 calls of 3.8 s, about 42 kbit/s. Idle not published: our 0.5 MB a day.5 |
| AMR 12.2 (3GPP PoC example) | 14.44 kbit/s | 6.5 MB | 0.5 MB | 3GPP’s push-to-talk example: AMR 12.2 with ten 20 ms frames per packet, 14.44 kbit/s with RTP/UDP/IPv4 headers.6 |
| Another app | 20 kbit/s | 9.0 MB | 0.5 MB | Most vendors publish no figure. We use 20 kbit/s, what wideband Opus at 16 kbit/s costs in 60 ms packets with headers, and 0.5 MB a day idle.4 |
Location. No push-to-talk vendor publishes the size of a location report. We use 200 bytes: about 175 bytes of data, as a tracking platform gives it, plus the packet headers.8 Photos count 250 kB each, our assumption. App updates, video and maps are not included: set the radio to update over Wi-Fi. Some operators round each small data session up to 1 or 10 kB, which adds to location reports.8
What vendors and dealers say
| Who | Figure | |
|---|---|---|
| Zello | 70–100 MB a month for an average user | 1 |
| Zebra PTT Pro | 10 hours of talk a month: 220 MB, plus about 20 MB idle | 3 |
| ESChat with Siyata (2022) | Typical users need about 0.6 GB a month | 11 |
| Inrico (maker) | About 1–2 MB per hour of voice calls | 10 |
| US dealer of Retevis PoC radios | 500 MB a month is usually plenty | 12 |
| Radioddity Tomolink (bundled SIM) | About 800 MB a month | 13 |
Published hourly figures differ about twentyfold, and only Microsoft says whether its figure counts receiving. That is why the result is a span when the app’s rate is.
Questions
How much data does a PoC radio use a month?
Usually tens to a few hundred megabytes. With Zello, 8-hour shifts on 22 days, 5 minutes of voice an hour and a location report every minute, a radio uses about 96–314 MB a month. Zello gives 70–100 MB a month for an average user; ESChat about 0.6 GB.111
Does listening use data, or only talking?
Both. A PoC call goes through a server: the talker’s radio uploads the voice and every other radio in the group downloads it. Microsoft says its walkie-talkie uses about 20 kbit/s when sending or receiving audio.4
How much data does Zello use?
Zello says it uses 12 to 45 kbit/s while audio flows, depending on the connection, about 20 kB an hour when idle, and 70–100 MB a month for an average user.1 Zello Work also sends a location report every 10 seconds by default, which an admin can change.2
