Asterisk 1.8.2.2-1 - sip show channels

Hi,
I’m running Asterisk 1.8.2.2-1
(asterisk18-core-1.8.2.2-1_centos5)

I have noticed CLI > sip show channels
Keeps accumulating entries as below

.21 (None) fc5cc50268a21c6 0x0 (nothing) No Rx: PUBLISH
.42 (None) db3a857cf9364c0 0x0 (nothing) No Rx: PUBLISH
.44 (None) 902387e9481bc99 0x0 (nothing) No Rx: PUBLISH
.29 (None) 9c948751f3b0449 0x0 (nothing) No Rx: PUBLISH
.32 (None) b49dfc8d4ab39fe 0x0 (nothing) No Rx: PUBLISH

After a few days I have > 443 active SIP Dialogs.
Handsets are GXP2000’s FW 1.2.3.5

CLI > core show channels works fine.