Preferred Serving System

This allows you to choose to accept roaming or restrict your phone to calls from your home network only.

Viewing preferred serving system

1. Tap Start > Settings > Personal tab > Phone > CDMA Services tab.
2. Tap Network System on the list of available services, and then Get Settings.
3. In Preferred Serving System tap Home only, Automatic-A, Automatic-B or Automatic, and then tap OK.