Even the best cellular networks are multiplexed for voice, not data, and any congestion will result in significantly lowered priority for data. When you combine this, link-layer complexities (whether ATM or not), and that your VoIP Provider is “somewhere on the Internet” and not on the other side of a switched network, the statements in my post apply.

Folks can go back and forth over what’s possible but the fact remains, and I stated very specifically, VoIP over Cellular results in significant overhead and would negatively impact the network (whether it’s just your connection or the tower). Thus, mass adoption is impractical because no matter how hard you try, it’s putting a square peg in a round hole.

Overall, calling out ATT over this is an auspicious act to make something free which while profitable (mobile voice), isn’t free to provide. I’m not saying ATT isn’t a coward, however the suggestion that Voice over Cellular is practical is an implausible dispute for ATT’s network. The real issues are that ILECs are state-regulated monopolies, ATT’s cellular network is really crappy, and POTS is still the status quo for calls. Even if you fix the first and last issue, and even with the permission ATT has recently given app developers to allow VoIP over Cellular, their data network still sucks and so will your VoIP calls.

As far as absolutism – no – and um, who said Never?

As far as I’m concerned, practical includes reliable between two phones when traveling. Good luck with that with VoIP over Cellular.

Cellular data can carry VOIP calls and in such a way that quality doesn’t affect the outcome significantly enough to disrupt call. In the end you pay for what you get. You aren’t going to get the sustained level of quality via the cellular voice or landline networks.

I use the cellular data network all the time to make voIP calls.

Are you basing this on some biased absolutism?

Never say never – celluar data networks have come a long way.

Latency, speed and capacity are no longer the issues they were in cutting edge networks.

I agree, but that still wouldn’t happen over the IP link. ATM over IP over would add even more overhead. Skype would stutter as soon as the cell phone leaves range of a tower.

Also, my reference to “oCell” is referring to cellular, not necessarily ATM. Even if it is ATM, the IP network which Skype’s iPhone app would have access to isn’t privy to the ATM network it resides.

wth are you talking about?

http://www.google.com/search?hl=en&client=safari&rls=en&q=cs+rt+phone+call&btnG=Search