Lest say you have 2 servers, A and B
Server A = It will transfer call to Server B = IP is aa.aa.aa.aa
Server B = It will receive call from Server A = IP is bb.bb.bb.bb
Create a dialplan (in default context) in server A
exten => _555888,1,NoOp(Transfers to Server B)
exten => _555888,2,AGI(agi-set_variables.agi,)
exten => _555888,3,Set(CALLERID(all)=${phone_number})
exten => _555888,4,Dial(
SIP/555888@bb.bb.bb.bb,300)
exten => _555888,5,Hangup()
Now you need to transfer the call to extension 555888 using ingroup/callmenu or anywhere in vicidial.
Create inbound carrier in Server B:
[transfers]
disallow=all
allow=ulaw
allow=alaw
type=peer
host=aa.aa.aa.aa
port=5060
dtmfmode=rfc2833
canreinvite=no
insecure=port,invite
Add 555888 as DID in Server B and point wherever you need to send the call..
Make sure to whitelist both server IPs for each other..