[Verizon Samsung Galaxy S III] amoamare:
ERI - Extended Roaming Indicator.

Maybe I can shed some light on this, as it looks like some people are not entirely sure what this does.

Q) Does this control roaming ?

A) Short No, Long answer No. The ERI controls certain things for the device in roaming areas. Hopefully I can break this down enough for you to understand essentially it does nothing "Service" wise. What it does is defined by "keys" in xml format. Perfect example that shows this is the iPhone in its bundle see below

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>name</key>
<string>Verizon</string>
<key>roaming_indicator_table</key>
<dict>
<key>0</key>
<dict>
<key>Data_Supported</key>
<false/>
<key>alert_id</key>
<integer>1</integer>
<key>call_prompt_id</key>
<integer>1</integer>
<key>character_encoding_type</key>
<integer>1</integer>
<key>icon_image_id</key>
<integer>1</integer>
<key>icon_mode</key>
<integer>1</integer>
<key>is_home_system</key>
<false/>
<key>text</key>
<string>Verizon</string>
</dict>
<key>1</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>1</integer>
<key>call_prompt_id</key>
<integer>1</integer>
<key>character_encoding_type</key>
<integer>1</integer>
<key>icon_image_id</key>
<integer>1</integer>
<key>icon_mode</key>
<integer>1</integer>
<key>is_home_system</key>
<true/>
<key>text</key>
<string>Verizon</string>
</dict>
<key>2</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>1</integer>
<key>call_prompt_id</key>
<integer>1</integer>
<key>character_encoding_type</key>
<integer>1</integer>
<key>icon_image_id</key>
<integer>1</integer>
<key>icon_mode</key>
<integer>1</integer>
<key>is_home_system</key>
<false/>
<key>text</key>
<string>Verizon</string>
</dict>
<key>64</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>0</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>1</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<true/>
<key>text</key>
<string>Verizon</string>
</dict>
<key>65</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>1</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>3</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<true/>
<key>text</key>
<string>Verizon</string>
</dict>
<key>66</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>4</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>1</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<false/>
<key>text</key>
<string>Extended</string>
</dict>
<key>67</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>4</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>0</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<false/>
<key>text</key>
<string>Extended</string>
</dict>
<key>68</key>
<dict>
<key>Data_Supported</key>
<false/>
<key>alert_id</key>
<integer>5</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>0</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<false/>
<key>text</key>
<string>Verizon</string>
</dict>
<key>69</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>4</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>2</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<false/>
<key>text</key>
<string>Extended</string>
</dict>
<key>70</key>
<dict>
<key>Data_Supported</key>
<false/>
<key>alert_id</key>
<integer>5</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>2</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<false/>
<key>text</key>
<string>Verizon</string>
</dict>
<key>71</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>4</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>1</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<false/>
<key>text</key>
<string>Extended</string>
</dict>
<key>72</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>4</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>0</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<false/>
<key>text</key>
<string>Extended</string>
</dict>
<key>73</key>
<dict>
<key>Data_Supported</key>
<false/>
<key>alert_id</key>
<integer>0</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>5</integer>
<key>icon_image_id</key>
<integer>0</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<false/>
<key>text</key>
<string>Verizon</string>
</dict>
<key>74</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>4</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>2</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<false/>
<key>text</key>
<string>Extended</string>
</dict>
<key>75</key>
<dict>
<key>Data_Supported</key>
<false/>
<key>alert_id</key>
<integer>5</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>2</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<false/>
<key>text</key>
<string>Verizon</string>
</dict>
<key>76</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>0</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>0</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<true/>
<key>text</key>
<string>Verizon</string>
</dict>
<key>77</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>0</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>2</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<true/>
<key>text</key>
<string>Verizon</string>
</dict>
<key>78</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>1</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>1</integer>
<key>icon_mode</key>
<integer>0</integer>
<key>is_home_system</key>
<true/>
<key>text</key>
<string>Verizon</string>
</dict>
<key>79</key>
<dict>
<key>Data_Supported</key>
<true/>
<key>alert_id</key>
<integer>1</integer>
<key>call_prompt_id</key>
<integer>0</integer>
<key>character_encoding_type</key>
<integer>2</integer>
<key>icon_image_id</key>
<integer>3</integer>
<key>icon_mode</key>
<integer>1</integer>
<key>is_home_system</key>
<true/>
<key>text</key>
<string>Verizon</string>
</dict>
</dict>
<key>version</key>
<integer>7</integer>
</dict>
</plist>

A simple break down of this. Key 0 < is a roaming int defining a value by the phone, it runs this against the ERI file, the ERI file then tells the phone to disable/enable certain functions and display a banner or Indicator if you are

A) Home Area > Usually displays "Verizon" in your banner

B) Extended Area > Usually display "Extended Area" in your banner

There is other "Roaming" names as well.

If you can see above ill break it down a little more

"Data Supported" = bool true or false, you guessed it tells the phone if it has data or not data.

"Alert ID" = bool true or false, tells the device if its roaming or not and to alert the user

"Is Home System" = bool true or false, tells the device if its in its home area.

A device can be in a extended area and be "Home System" this is due to roaming agreements.

This might not be the best explanation i'm running short of sleep but this is the best i can do to explain what a ERI does.