Halfway houses operate differently from prisons and jails, and the communication rules vary from one facility to the next. The quickest way to figure out what is allowed is to call the halfway house directly and ask to speak with a counselor.
The counselor can walk you through how residents are permitted to receive calls, whether there are designated phone times, and whether your brother needs to add you to an approved contact list before any communication can happen. Some halfway houses allow fairly open phone access, others are more restricted, and knowing the specific rules upfront saves you a lot of frustration.
If you do not have the phone number for the facility, a search for residential reentry centers in Lane County Oregon, should pull up the right location. The Bureau of Prisons website also has a facility locator if he is in a federal halfway house, which is worth checking first, given that it will have contact information and basic details about the facility.
Once you get through to a counselor, be straightforward about who you are and your relationship to him. Family contact is generally encouraged at the halfway house stage since reentry is the whole point, and staff are usually willing to help facilitate that communication.