The Grandstream GRP2615 is a desk and wall mountable audio phone with 10 programmable buttons. The GRP2615 includes Wifi, Bluetooth, and expansion port for a 20-button side car. Key differences between the GRP and GXP series is WiFi, sleeker look, and upgraded firmware.
Spec Sheet - http://www.grandstream.com/sites/default/files/Resources/Datasheet_GRP2615_English.pdf
User Manual - http://www.grandstream.com/sites/default/files/Resources/GRP261x_user_guide.pdf
Admin Manual - http://www.grandstream.com/sites/default/files/Resources/GRP261x_admin_guide.pdf
Bluetooth Compatibility - http://www.grandstream.com/sites/default/files/Resources/GRP2600_Bluetooth_Guide.pdf
Wifi Setup Guide - Instructions located in User Guide
Voicemail - How to setup and retrieve voicemails
Transfer - How to send a caller to another extension
Call Park - How to send a call to a parking spot, and retrieve it on another phone
Ring Group - How to send calls to a group of phones
Conference Call - How to create a 3-way call between parties
Recordings - How to create recordings for IVR's and Announcements
Feature Codes - Star/Feature codes to enable and disable admin features