Why did they pick on Vonage?

Ike Elliott has a great post on why companies get into patent litigation. These 5 questions explain why VZ went after Vonage, but not Packet8 or Broadsoft or Cisco (for that matter, why VZ doesn't go after ATT or Sprint):

How does a patent holder decide who to target? They usually consider the following:

1. Are we pretty sure the target is infringing our patent?
2. Are we infringing any of the target's patents?
3. Can we win a lawsuit if it goes to court?
4. Is it important to maintain positive relations with the target?
5. Is the target a competitor that we would like to impair?

You might also like to read Ike's post: Are Verizon's VoIP Patents Valid?