Grandstream GXP2135 8-Pack of phones. 32 virtual BLF/speed-dial keys, up to eight lines/line keys and four SIP accounts. Built-in Bluetooth easily syncs with mobile phones and headsets. 4-way conferencing capabilities and supports EHS compatible Plantronic's headsets. If used with Grandstreams UCM series IP PBX appliances, you can enjoy even more features such as Zero-Configuration provisioning, 1-touch call recording and more.