If the Sidekick is REACHABLE, but the IP Phones are NOT Visible (all red X), or stuck on “Pending” status, then the Sidekick is in a different broadcast domain from the IP Phones.  Likely causes include:

• Being given an IP address in a different subnet from the DHCP server than the IP Phones
• The Sidekick’s port on the Ethernet switch is in more than just the VoIP VLAN