Need Incoming settings - SIP termination Gateway

I want my box to act as SIP terminating gateway. My partner will send IP traffic and I’ll route the incoming calls to my trunks for termination.

How do I,

Set my box to accept my partner’s traffic ? He is providing me with the IP only and says that there is no need for username/password.

Do I have to create a trunk with incoming settings below,

host = Partner IP Address
type = peer
canreinvite = no

Once, I start getting his calls from the trunk, how do I route them to the appropriate trunk ?
Do I have to write a custom incoming context such as ?

exten => _NXX,1,dial(SIP/trunkname2/${EXTEN}

something like that ?