Custom-DID Inbound route

Hello all,

writing specific rules is not my strongest point so I came here to get some help!
Right, let’s start with the what, where and how:

I have a “From” field that contains "HuntGroupname - CallerID "

The separation is done with a - as you can see.
What I want is to use the “HuntGroup01” part as DID.

At the moment this is the default rule for the DID:

and so I came up with roughly this:
Look at “From” field. Cut everything after the - sign and use everything before the - as DID.
exten = s,n,Set(TRUNKDID=${CUT(SIP_HEADER(From)|-|1)}?${CALLERID(name)}:${ARG2})})
This rule is not vaild ofcourse because ARG2 is nowhere defined

I cannot really decipher how to accomplish the cut and paste part.
If someone has another idea I 'd like to hear that