I am testing out a polycom 650 with a side car. In the phone provisioning it seems that blf 5 and 6 dont do anything. On the phone line button 1 and 2 are the extension. 3-6 (BLF1-4) get what ever I configure them to be. BLF 5 and 6 seem to go nowhere, and then then side car starts at BLF 7. Is this normal for these phones?