Thank you, pc44, for your reply. I have tested and confirmed that the short form, 18[00|88|77|66|55]xxxxxxx, does not working. I put 18[00|88|77|66|55]xxxxxxx(Msp2)|<**1>1[2-9]xxxxxxxxx(Msp1) and the call goes to SP1.
So here is my question: according to the same OBI Admin Guide you referred, the caller-list can be formed like this:
caller-list := caller|caller|caller|...
which I thought may suggest we can have multiple digits, like a caller number, as an option in a pair of brackets, but practically it's not working. WHY?