What is VoIP or SIP Phone?
VoIP phone can use different control protocols such as SIP or other proprietary protocols.
SIP Phone is a VoIP phone based on a Session Initiation Protocol that provides a SIP-based VoIP network. (see What is SIP? for more details)
VoIP phones can be a software-based - programs/applications named softphones or hardware devices also called desk-phones.
IMX is compatible with ANY SIP 2 compliant phone (softphones and hardware devices)!