Comments on: VoIP over EVDO: Are we there yet??

Question: VoIP over EVDO: Are we there yet??

allterrainbrain — Sat, 18 Nov 2006 08:15:52 -0800

VoIP over EVDO. If you've tried it (especially on Sprint's Rev A EVDO), how do you like it? I'd be using Skype, using it rarely, and only using it during calls -- not leaving it idling and using bandwidth. (With my current Sprint phone-as-modem setup on 1xRTT, I average 400-600ms pings -- i.e., too much latency for VoIP even if I had enough bandwidth. But on Sprint's now active EVDO Rev A, they claim latency of 100-150ms and upstream averaging 300-400k.) Yes, I know EVDO is not in the TOS. And I connect primarily from NYC in strong-signal areas.

By: b1tr0t

b1tr0t — Sat, 18 Nov 2006 09:34:24 -0800

You might want to try a more modern VoIP service than Skype, like Gizmo.

Skype selects its codec based on how much outgoing bandwidth it thinks you have. It doesn't characterize the link beyond that. It won't know if you are on a high-latency link, or if there is a chokepoint between you and your destination.

That having been said, even with a VoIP system that dynamically characterizes the link and selects the best codec, call quality on a link with 400-600ms of latency is going to be terrible.

By: allterrainbrain

allterrainbrain — Sat, 18 Nov 2006 11:58:23 -0800

My *current* connection is 400-600ms, as I said, and I agreed with you that that's too much for VoIP. I'm asking about people's experiences using EVDO, especially Rev A.

Thanks for the pointer to Gizmo!

By: b1tr0t

b1tr0t — Sat, 18 Nov 2006 14:27:18 -0800

When I was doing VoIP demos last year, we tried out a number of different cellular PCMICA cards, up and down the west coast (mostly LA, Seattle, and the Bay Area). IIRC, 400-600ms was best case. 1000-2000 ms was much more typical, and even 600ms links would spike at 1000-2000ms unpredictably. EVDO was among the technologies we looked at, but I don't know what revision.

I think the cell providers will do everything they can to keep VoIP off their data networks, as it threatens to completely undermine their business model.

By: allterrainbrain

allterrainbrain — Sat, 18 Nov 2006 21:56:11 -0800

Yeah, I think Rev A is the first cellular data network that will be usable for VoIP. People are reporting consistent real world latency in the 100-200ms. If you google the exact phrase "voip over evdo," you see people doing various speed/quality tests with previous versions of EVDO, which are usually characterized as "almost there" with latency being the issue. This imples Rev A could be the first usable network for VoIP.

I was hoping to get some responses here from early adopters of Rev A, but it's probably a few weeks too early to have asked the question. I'll try again soon. I really appreciate the pointer to Gizmo and I'll be watching it carefully (especially as it gains more area codes for Call In numbers), since it looks preferable to Skype for several reasons. Thanks!