My phone sometimes has different types of rings

 

You’ll hear different types of phone rings if you subscribe to:

• Call Waiting
  Where technology permits, you’ll hear different rings for local and long distance calls if you subscribe to Call Waiting for your home phone.
  
  If you are already talking on the phone, a short beep means there is an incoming local call; a long beep followed by two short beeps signifies a long distance call.
  
  
• Ident-A-Call
  With Ident-A-Call, you can have up to three phone numbers on a single line, each with its own distinctive ring.