The Grandstream GRP2601 IP phone features 5-way audio conferencing, GDMS device management, and EHS headset support. Grandstream. The Grandstream GRP2601 IP phone comes with two SIP accounts and two lines, making it the ideal choice for simultaneous multi-calling. Users can also conduct conference calls with exceptional audio clarity thanks to 5-way audio conferencing support, enhancing effective communication both in meetings and with colleagues and clients.