Connecting 2 Grandstream GXP-2000

Hi,
I have connected 2 Grandstream GXP-2000 phone by switch.
and gave ip address

Grandstream GXP-2000 -1
192.168.100.2
255.255.255.0
in Grandstream GXP-2000 -2
192.168.100.3
255.255.255.0

Grandstream GXP-2000-1 <–Switch–>Grandstream GXP-2000-2

now from Grandstream GXP-2000 -1 i dial 192168100.3 ,then press the send button.

But Grandstream GXP-2000-2 did not response(ringing!!).

Did i miss any step ! Please help.