How to convert caller id of SIP phone

I had setup two asterisk servers. Server A connect to a PBX throut PRI. Server B act as a SIP gateway that many SIP phone register to. Server A and server B conntected by ip network. Now, my sip phone can place call from server B to server A to PBX. My PBX can see caller id of sip phone.How can i convert caller id of every sip phone to a same number.
Below is my configure.

sip.conf in server B

[50005000]
type=friend
username=50005000
secret=50005000
;callerid=1111111
host=dynamic
context=incoming
;disallow=all
allow=all

[international]
type=peer
host=192.168.142.8
callerid=11111

extensions.conf in server B

exten => _00.,1,Dial(SIP/${EXTEN}@international,60,r)
exten => _00.,2,Hangup()

sip.conf in server A

[sip_proxy2]
type=friend
context=incoming
host=192.18.121.132

I make call from SIP phone 50005000 and PBX see caller id 50005000, in fact, i want it can convert to 11111.

Would using the below in your dialplan not sort out that problem…

exten => 1,1,Set(CALLERID(number)=5678)

Hope this helps…

SuperX