KNOWN LIMITATIONS
• The first two keys are configured as line keys (via the template). This cannot be changed, otherwise
the phone will not be able to make calls.
• When configuring the Grandstream GRP phones as STUN, the RTP Port range will always be 24
ports, starting from the “Local RTP Audio Ports Start” value you set in the extension’s settings.
• If BLF Transfer mode is set to “Attended Transfer,” Shared Parking BLFs will not auto complete
the call and must be manually completed.
REFERENCES
3CX Ltd. 2018, How to configure Grandstream GRP261X Series for 3CX, accessed 26 March 2021,
<https://www.3cx.com/sip-phones/grandstream-grp26-series/>.