CME paging only working on some phones

[murraymwps]

I have a CME that is configured for paging. But only some of the phones "pick up" when the paging extension is dialed. In the below config, ephone 13 picks up but ephone 79 does not. 

Config:

ephone-dn 54

 number 340

 paging

ephone-dn 12

 number 1152

 call-forward busy 2100

 call-forward noan 2100 timeout 10

 mwi sip

ephone-dn 87

 number 0902 secondary 0902

 call-forward busy 2100

 call-forward noan 2100 timeout 20

 mwi sip

 hold-alert 30 originator

ephone  13

 mac-address 001D.4596.3EEF

 paging-dn 54

 type 7940

 button  1:12

!

ephone  79

 mac-address 000B.46E9.B133

 paging-dn 54

 button  1:87

[murraymwps]

I just read the following in the Cisco doc:

Router(config-ephone-dn)# paging ip 239.1.1.10 port 2000

"Specifies that this ephone-dn is to be used to broadcast paging messages to the idle IP phones that are associated with the paging dn-tag. If the optional keywords and arguments are not used, IP phones are paged individually using IP unicast transmission (to a maximum of ten IP phones)."

Does that mean that my config uses unicast and therefore I can only page 10 IP phones?