Unlocked SMT5600 doesn't connect to Cingular

[Guest steklo5]

Gents,

Need help with an SMT5600 from AT&T. I unlocked it to use on the Cingular network in US. The phone boots up normally and recognizes a Cingular SIM but for whatever reason always connects to the T-Mobile network in automatic mode displaying the roaming triangle. Interesting enough, there are Cingular networks in the list of preferred ones.

In manual mode, the only two networks listed are T-Mobile and AT&T Wireless. If I choose AT&T(which is one company with Cingular now) the phone still displays the roaming triangle. And it switches back to T-Mobile at a first opportunity. The same SIM card works in an unlocked HP H6315 from T-Mobile and picks up Cingular.

Any advise is much appreciated.

[Guest Chaser81]

What band does Cingular use? (Excuse me if that is a stupid question, I am in the UK and dont know about the American networks) The SMT5600 can only operate on 900/1800/1900. Does Cingular use 850?

[Guest smeg36]

Actually, the SMT5600 has 850. The C500 has 900. Cingular does operate at 850. My guess is the Cingular service in that area is provided by a tower agreement with T-Mobile. If you had a Cingular phone, it would most likely say Cingular on it, but since you don't it recognizes it as the T-Mobile tower. I would call Cingular to be sure they do have a tower agreement just to be sure you won't get roaming charges or anything.

[Guest jleecong]

Actually, the SMT5600 has 850.  The C500 has 900.  Cingular does operate at 850.  My guess is the Cingular service in that area is provided by a tower agreement with T-Mobile.  If you had a Cingular phone, it would most likely say Cingular on it, but since you don't it recognizes it as the T-Mobile tower.  I would call Cingular to be sure they do have a tower agreement just to be sure you won't get roaming charges or anything.

X2

My Nokia 3650 with AT&T SIM shows Cingular but in my SMT-5600 it shows AT&T. Same towers/area just the phone displays something different.

[Guest five337]

I have an unlocked SMT5600 with T-Mobile and only Cingular appears with the roaming triangle.

My MPX-220 shows T-Mobile with the same SIM card - No roaming.

My MPX-200 shows T-Mobile with a roaming triangle.

Anyways - it really doesn't matter what it says - just dial 611 to make sure you are on the correct provider, the display name is just cosmetic (or so I am told).

-lee

[Guest steklo5]

Just came back from a skiing trip to Canada. As I was driving I watched the service on the phone. It showed anything from T-Mobile to AT&T to Cingular to various six digit codes. I suspect it showed Cingular because I tweaked the Registry to do so for 310410. The roaming triangle never went away.

My guess is that AT&T, which marketed the phone, hardcoded these preferences in ROM. It's not clear whether Cingular will sell this phone or will they stick to the Mpx220. Therefore, I'm not sure whether there will be a ROM update.

So be it. Not a big deal, just a bit annoying.

[Guest nickcornaglia]

Go into Settings>Phone

Make sure you have ALL the cingular entries checked as the preferred netowrk