Broadsoft
BroadSoft Partner Configuration Guide - Yealink SIP-T4x IP Phone
http://www.grandstream.cn/knowledgebase/general_interop_broadsoft.pdf
http://www.grandstream.com/sites/default/files/Resources/gxp2200_usermanual_english.pdf
http://www.grandstream.cn/knowledgebase/ht50x_interop_broadworks.pdf
https://wiki.unify.com/wiki/Broadsoft_DMS