Network Selection

so, For a T-mo customer, If a call orignates in the Carolinas (on the Cingular network). The call should stay connected as long as there is cingular signal, where ever you may go.

Up I-95 & I-85 past the Virginia state line, there'll be both tmo & cingular. a call should still work on cingular until you hang up. (i would assume)

 

this is for all technologies........you see each company has their own switches that a couple towers are connected to...........handoffs between towers on a single switch are completely smooth.......handoffs between different switches on that carrier are hard handoffs but they are made nonetheless........sometimes a call will drop when handing off between towers on different switches but companies do their best to make this as smooth as possible...........

when you switch between two switches on completely different networks the call has to drop.........the only way to make handoffs between carriers even remotely possible.......each carrier in the U.S. would have to be in constant fiber-speed communication with eachother (well at least all the carriers on one technology)..........and even if they managed this.......the handoff prolli would never be perfected

 

Sorry I misread your post, but based on my experience it wouldnt work. It might just be t-mobile because even if your on a call in a roaming area and you come up on just a lil bit of signal it just drops the call to go onto the T-mobile signal. So with GSM as a technology yes it should stay connected, but t-mobile doesnt want ya to do that.

 

It won't stay connected if cingular does not have a roaming agreement where you are going whether the roaming agreement is in force in one place and not in the next. There are areas of the Carolinas where cingular is available but the preferred network is Suncom and the phone will prefer Suncom because that's who T-Mobile has the roaming agreement with. I know a T-Mobile user in the western part of NC who lost the ability to roam since the roaming agreements were changed to Suncom in preference to cingular. Perhaps T-Mobile struck a better deal with Suncom so T-Mobile deferred to them. If cingular or Suncom covers an area it's entirely up to the guest's carrier (i.e. T-Mobile) to make whatever roaming agreements are necessary.

 

Cingular & SunCom are both preferred here in the Carolinas. Depending on the phone your using, either one may be used. I found this out with 2 of my friend's phones. One was on SunCom 100% and the other was 50/50 SunCom & Cingular. This was back in early January

Nearby in the Knoxville area in Tennessee, (where the is no SunCom or T-Mobile). A phone will only stay on Cingular.

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Now i know a Cingular signal won't work for tmobile customers where there is a t-mobile signal. but Hopefully the fact that phones can't switch to another carrier's tower during a call is true when traveling to any t-mo service area.

It's TDMA behavior to drop a call when going out of a carrier's service area.

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Also, is it just a T-mobile thing. Because i can force my Alltel phone to roam onto Sprint or Verizon where ever in the US (even in the Alltel home area) and its perfectly fine.

And with roaming agreements, i thought any agreements are national, not for regional areas. (unless it's a tmobile issue, i guess). because the goal for every carrier is to provide "national" service/coverage. I think it's just dumb to provide "partial" access to a network (aka regional, like tmo vs cingular in NJ). If a carrier wants to provide national coverage, a "national" agreement is always the best option

It some areas, this may improve dead spots/coverage holes

 

you see i think thats the thing with CDMA........when they make agreements.........its national whereas when GSM makes agreements......they only cover certain areas.........

and just to clear up the whole priority issue......in GSM.........they dont prioritize.......the device will connect to the first tower it discovers that it either native or is permissable by roaming agreements but you can change networks at any time.......except for Cingular.......they have some sort of prioritizing system with their SIM cards but nobody entirely understands it........

 

I can not select Cingular when their is no signal with the T-Mobile phone, they ended their roaming agreement after Cingular sold the JV network to T-Mobile. I believe they don't want T-Mobile customers to have access to the Cingular network for a few reasons.

And to answer the 2nd question, as long as the T-Mobile customer doesn't loose a signal where there is no roaming agreement or T-Mobile native coverage then the call would stay connected.

If the call started on the Cingular network, as soon as the call connected to a T-Mobile tower the call would stay with T-Mobiles network as long as their is a signal or again a roaming agreement was in place & the call had to switch to the roaming tower.

Usually if your on the interstates or other major highway, you won't have an issue with staying on the call or network, it's once you go off them you can loose the call & be stuck, again when their is no roaming agreement like here in NJ.

 

Actually, i just went to Columbia, SC yesterday and could not use Sprint like i could in the upstate, o well.

And i know why; the NID number is different.

so, even if an SID should work, i guess NID is the final thing that'll determine whose signal you can use

 

whats an NID???

 

NID is "Network ID." it is used in CDMA phones & technology.

I believe it is for certain (smaller) areas within an SID number.



Example for Upstate SC:

Sprint SID: 4376

NID: 1

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Example for Columbia, SC:

Sprint SID: 4376

NID: 68

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i think it will finally determine where you can actually roam with your CDMA phone; more defined than just an SID.


It's like this, a CDMA phone knows which SID it can use via a PRL (preferred roaming list). Some SIDs are not in the PRL.

I guess NIDs work the same way; every SID (system ID) contains NID numbers. Some of those numbers are compatable and some aren't.


think of NIDs like a circle inside a circle

Both SIDs & NIDs are part of a certain area's coverage. SID areas are usually larger than NIDs



A big SID area (like Sprint's) may contain quite a few NIDs.


correct me if i'm wrong on any of that...

Anybody else have more info, i can't think of anything else right now

 

alright thanks for the info...........