Once you have your AT&T SIM in your phone with network bars showing, you will need a data plan and Access Point Name (APN). These are the APN settings for AT&T Mexico. AT&T Mexico AT&T Mexico APN Internet Settings for iPhone For an iPhone, go to Settings > Mobile Data > Mobile Data Network then input the APN settings below. APN: modem.nexteldata.com.mxUsername: (Leave it blank)Password: (Leave it blank) You can also easily access your SIM applications. To reset your APN settings on iPhone or iOS device, go to Settings > Mobile Data > Mobile Data Network > Reset settings then input the settings above so you can be connected to the internet. AT&T Mexico APN Internet Settings for Android Smartphones If you have an Android smartphone or Tablet with AT&T Mexico SIM installed, go to Settings > Mobile Data > Access Point Name > Add new then add the settings below. This could be located elsewhere depending on the version of Android and Android device manufacturer. Here are AT&T Mexico APN Internet Settings for Android Smartphones: Name: AT&T MXAPN: modem.nexteldata.com.mxUsername: (Not set - Leave it blank)Password: (Not set - Leave it blank)Proxy : (leave it blank \u2013 not set )Port : (Leave it blank \u2013 not set)Server : (leave it blank )MMSC : ( Leave it blank )Multimedia Message proxy : (leave blank)Multimedia message port : (Not Set)MCC: 334MNC: 090Authentication type : (none)APN type : (default)APN protocol : (IPv4)Bearer : (Unspecified)Mobile virtual network operator : (none ) Save these settings, select them as active then restart your phone. You should also be within network coverage and with an active data plan in order to browse the internet.