On the LCD Screen of the phone, directly beneath where it says "Grandstream" you should see the device's IP address which will be in the following format: "192.168.1.10".
Note that the actual numbers you see will most likely be different.
I have a problem with Grandstream phones (GXP2130, GPX2140) not getting the timezone setting correctly.
Having investigated this it appears that the is generated correctly by ENdpoint Manager but the cfgxxxxxxxxxxxx file it then generates is incorrect.
3CX Phone System includes functionality to easily set the Time Zone and DST (Daylight Savings Time) parameters on phones via provisioning.
By default, 3CX Phone System is configured for US Eastern Time.
There are several options for upgrading the firmware on the Grandstream GXP 1405: TFTP, HTTP and HTTPS.
These instructions cover using a simple web-server with no authentication.The GXP1450 is a two-line device that is part of a new line of Office IP phones from Grandstream.In our experience we found this device to be reliable, full featured, easy to configure, and affordable.Log in to your Grandstream device by entering the phone’s IP address into your chosen web browser.You will find the address on the screen of the phone. I have the timezone set as follows:-P64 = GMT 0BST-1, M3.5.0/, M10.5.0/ I think the Endpoint Manager generated cfgxxxxxxxxxxxx file has some extra/odd characters in this string and hence not recognised correctly by the phones.