You either have to setup a leading code or send all dialed numbers that match a certain pattern to the distant OBi. In this example I am sending all calls that start with 1xxxxxxxxxx to the other OBi using the OBiTalk network.
Here is one way to do it, there are other ways.
I appended **3 to all dialed numbers that started with 1xxxxxxxxxx. Then in the Phone port outbound routing I routed **3 to an unused VGx Gateway (VG3 in this case) which then sends the call to the distant OBi.
DigitMap: |<**3>1xxxxxxxxxx|
OutboundRouting: {(<**3:>(Mvg3)):vg3}
Then I setup Voice Gateway 3 (VG3) to send the call to the other OBi using OBiTalk Network
Name: One Stage to OBi110 to SP1
AccessNumber: PP(ob200123456)
where ob200123456 is the OBiNumber of the other OBi.
Then on the receiving OBi you need to setup the OBiTalk InboundCallRoute to pickup the dialed number and dial it on the SPx you wish, SP1 in the example here
InboundCallRoute: {(300123456)>(msp1):sp1},{ph}
which says if the call is coming from my other OBi (300123456) then send the number to SP1 to dial, otherwise ring the phone.
After you set it up you should run some test calls and look in the Call History on the OBi to see if it routed the call properly.