EVDO vs. 1xRTT Roaming

itb44 · EVDO User Joined: 31 Jan 2008 Posts: 50

I've read that AllTel and Sprint customers have been able to roam on Verizon's towers for data, not just at 1xRTT speed, but sometimes (given the right hardware/firmware and PRL) at EVDO speed.

Does it work, or has it ever worked, the other way around? That is, could/can a Verizon customer normally roam on a Sprint (or AllTel or Telus) tower at EVDO speed?

When I took my Verizon card to Canada, I was only able to roam on Telus at 1xRTT, even though Telus has good EVDO service there. Back in the States, when I wasn't able to pull in a Verizon signal, my card only roamed on Sprint at 1xRTT where I believe there was good Sprint EVDO service.

Assuming that the right firmware and PRL versions were loaded (even if old versions), would a Verizon customer who did manage to roam on another provider's EVDO tower at EVDO speeds incur any unexpected charges just for using EVDO rather than 1xRTT?
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AC595, WRT54G3G

itb44 · EVDO User Joined: 31 Jan 2008 Posts: 50

I'm going to partly answer my own question. I've done more research, a little experimenting, and some actual analysis of a few Preferred Roaming Lists (PRLs). I do realize that the PRLs alone don't necessarily give the full picture, since they may be further limited by device firmware settings.

In general, it appears that Alltel devices can EVDO roam on some Verizon, Sprint and US Cellular subnets; Verizon devices can EVDO roam on some Alltel and US Cellular subnets; and Sprint devices can EVDO roam on some Alltel and US Cellular subnets. All other roaming between these four providers appears to be limited to 1xRTT.

With the exception of US Cellular (which may only have one EVDO subnet), the other providers only open up a limited number of their subnets for EVDO roaming (probably those in particular geographic areas). Either that, or the other providers are not getting sufficiently updated info from each other on the available subnets. A picture might illustrate it better, but there are some surprising inequalities in all that. For example, while everyone else can EVDO roam on the US Cellular subnet, US Cellular devices cannot EVDO roam elsewhere (just 1xRTT).
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AC595, WRT54G3G

falsedragon · EVDO User Joined: 13 Oct 2008 Posts: 45

Its all up to the roaming agreement. The PRL is only there for the AT to scan that channel, and it what order. If you alter a PRL to add the SID/Channel/ect, you still have to pass authentication.

In my experience changing the PRL is only good if you want to change the priority. Or get rid of something.