[mberlant]

Are you permitted to use your EVDO to access Verizon's 1xRTT network? I used that network for about two years and had wonderful connectivity at about 116kbps each way. Low latency and not much jitter, considering the mobile environment.

[rudholm]

Not that I know of. There doesn't appear to be any selection option on the phone or on the Cardbus card.

[fortissimo]

GPRS has about 800mS - 1000mS latency
1xRTT has about 200 - 300mS latency
I don't know much about EV-DO yet, as it's not avail. here (Canada) yet.

I found GPRS is not reliable, as it goes up and down in performance. I can stream online radio sites very well via GPRS at 56kbps air speed (translated to about 33kbps throughput) downstream , with a 4+1 Class 8 terminal . However, it does flutuates and the reason why online radio works is the big buffer on the player!

I advise against any VoIP over mobile phones unless you have EV-DO , 1xRTT or UMTS ; GPRS with EDGE might do ok also, however, still lives with the long latency. Unless you are doing PTT (walkie-talkie) mode, phone conversation is going to be mentally difficult when latency is over 250mS, and quite bad at 500mS (check ITU recommendation yourself).

If I were you, I'd go for a Mobile Voice to Landline / Mobile Voice channel, and then hop on to VoIP via a VoIP FXO gateway such as a Sipura 3000 (and/or a Dock-n-Talk if you go the Mobile to Mobile like some recommended. To me it's less preferable than landline b/c of one more wireless device, but if price over quality is the key, may be the mobile can be cheaper than a landline in some places).

In my area, one GPRS provider is very unreliable, and so using it for VoIP is very difficult. We have tried using a VoIP unit called VoIP Blaster by Creative Labs , which uses G.723a , a very very small bandwidth codecs, and H.323 gateway, and it just can't go over well. I'll try it again in the future to see if there is any improvement on another GPRS provider and see.

1xRTT might be the answer. If the user is in the US, I think Sprint PCSVision has it for a very cheap rate, if you know the trick (check the Sprintuser.org site , not sure if correct domain name).

No matter what you use, you should try to use the smallest bandwidth codec that you can tolerate if you are going over wireless network providers. I recommend G.723 , or GSM (not the wireless network, but as a codec), and the G.729 for better quality.

Good luck for the experiment, but I won't use it for important business calls though.

EV-DO is available in quite a few cities now in the US by Verizon. UMTS is available in a few cities as well by AT&T (now Cingular but was from AT&T). There is a EV-DO PC Card available, and more terminals coming I think.

Sprint PCS Vision is 1xRTT and I am very surprised if you have 1 second latency. How did you get that information? Did you do a PING plot or jitter test or a line quality test? 1xRTT should be about 200 - 300mS . It is possible that your PCS Vision has fallen back to CDMA CSD and thus has a much longer latency, b/c the area does not have 1x .

This is my first post at this site, so please correct me if I have made any mistakes here.