Help ARC LT15a 3G problems on AT&T

[SonyARC]

Hello ARC Users,

I recently acquired an unlocked ARC LT15a and tried to set it up on AT&T. I can successfully make phone calls, send/receive text messages, and browse the web - unfortunately only on EDGE 2G. I took it to the AT&T store and the rep spent about 2 hours changing APN settings and what not, but in the end could not get 3G to work. As I understand it the LT15a should have no problem working on AT&Ts 3G network, but it's just not working. Any thoughts??

 

[SonyARC]

I was able to fix the problem. The phone was set to GSM only, but needs to be on GSM and W-CDMA mode. I thought CDMA mode was for other carriers (who use CDMA, like Verizon) and would only drain the battery.

 

[AHQ]

Hi there,

I just bought an Arc LT15a and I started using it today. My previous phone was an unlocked Nokia E71, which I've been using on AT&T's network for nearly three years. I have the $15 unlimited "featurephone" data plan, which I've used with my E71 ever since day one.

I am currently unable to use AT&T's data network on my Arc. Neither 2G or 3G will work. My Nokia detected the data and MMS settings right away and I was able to go online without any problem, whereas the Arc cannot connect to anything (except for WiFi). When I tried going through the setup wizard, the Arc would not complete Step 3; it would attempt to download settings for Internet and multimedia messaging, but I'd repeatedly get a connection error/retry message.

I have a feeling that my SIM card might be the culprit. It's a Cingular-branded SIM that is several years old. My E71 was able to maintain both 3G and EDGE data connections without any setup on my part, but the E71 has HSPA 3.6 Mbps modem, whereas the Arc has an HSPA 7.2 Mbps modem. I'm guessing that the Arc might require a newer SIM card.

Any thoughts?

 

[AHQ]

.
I found the following settings on Sony Ericsson's forums. I had to manually enter the following information. Worked like a charm.

settings -> wireless & networks -> mobile networks -> access point names -> MENU -> add New

Name: AT&T
APN: wap.cingular
Proxy: leave blank
Port: leave blank
Username:WAP@CINGULARGPRS.COM
Password:CINGULAR1
Server: leave blank
MMSC: http://mmsc.cingular.com
MMS Proxy: wireless.cingular.com
MMS Port: 80
MCC:310
MNC:410
APN Type: leave blank

MENU -> save

 

[paker]

I have LT15a unlocked and followed the step above. Still cannot get on internet. Now Access Point Name > Settings stopped. All is wiped under Access Point Name. Any idea how to get on AT&T network? Thanks.