It appears that your boyfriend has either been in jail for a criminal matter and then had an immigration hold placed on him or was arrested directly by ICE. In either case, ICE is probably preparing a charging document, called a Notice to Appear or NTA, for your boyfriend to have him placed in removal proceedings. Sometimes ICE takes longer to prepare such a document, but ICE is supposed to issue the document soon after detaining someone. The charging document will have the alien registration number on it. If you are able to communicate with your boyfriend, ask him what his alien registration number is or what is the alien registration number stated on the charging document. The number is the letter "A" followed by nine-digit number with the first digit being a 0.
If that doesn't work and if you know the actual name of the facility in which your boyfriend is being held, contact that facility and ask for his alien registration number. Typically, if you speak nicely on the telephone and provide the detainee's name and date of birth, the ICE facility will provide you the alien registration number and the location of where the detainee is being detained if not at the facility which you called. For example, if your boyfriend is being held at the Tacoma Detention Facility, go to this link: http://www.ice.gov/pi/dro/facilities/tacoma.htm. That website will provide you with all the contact information necessary to get in touch with someone at that facility who would be able to help you.
Now, regarding the bond, the bond qualification and amount is first determined by an ICE deportation officer and then can be redetermined by an Immigration Judge only after the charging document has been filed with the Immigration Court. Typically, when the ICE deportation officer gives the charging document to a detainee, he will also give the detainee his bond-determination form stating whether the detainee is eligible for bond and if so, for what amount. Again, when you contact the detention facility to find out your boyfriend's alien registration number, ask for the name of the deportation officer assigned to him and ask for that deportation officer's number or extension. You can also ask whether bond has been granted and in what amount, but most of the time, only the detainee and the deportation officer would not such information, so if you can't get in touch with your boyfriend, then talk with the deportation officer. Please note that because you are not related to your boyfriend, the ICE officers could simply inform you that they are not permitted to provide you any information. In such a case, have your boyfriend's mother, father, or sibling call.