APN Settings for Build Lumia 920s on AT&T — Plus Internet Sharing Workaround

The Nokia Lumia 920 developer phones that were given out at Build 2012 are unlocked GSM phones, specially created for attendees of Build. As such, they are not AT&T branded and come with a special “access point” settings app to select (and create/edit custom) APNs for mobile networks.

Unfortunately, the LTE APNs that are pre-loaded seem to have a problem … as of this past Friday, MMS messaging has been failing for some (all?) AT&T users.  I believe I have found the proper settings to get LTE working as well as MMS.

To set up, go to Settings -> Access Point and add a new APN, give it a name and give it the following settings:

Internet APN -> Access Point Name: pta

MMS APN -> MMS Access Point Name: pta

MMS APN -> Proxy address: proxy.mobile.att.net

MMS APN -> Proxy port: 80

MMS APN -> MMSC address: http://mmsc.mobile.att.net

All other fields should be left blank.

Save the new APN and then tap the new APN to activate it. I’m n0t sure if it’s necessary, but some people recommend rebooting your phone after changing the APN.

This new APN should support LTE and MMS with no problems.

As a bonus, there seems to be a workaround to enable Internet Sharing (so long as it’s enabled in your plan).  After the new APN setup (above), go into Settings -> Keyboard and add a new keyboard language that requires a download (such as Spanish). The download will force an update, which will enable you to turn on Internet Sharing (not sure why, but it does!).