HBC Interface Box Installation Created with Sketch. The handset-based console interface boxes connects the handset-based console to the SRG3900/SCG22 and attaches to the HBC cradle. Find a partner More accessories ItemPart no.HBC Interface Box300-00670Compatible with these accessoriesPlease select one more product to compare with. Handset-Based Console 3 More details Please select one more product to compare with. SRG/SCG Hands-Free Kit (Console) More details Compatible with these productsPlease select one more product to compare with. SRG3900 Discontinued More details Please select one more product to compare with. SCG22 More details