http://www.grandstream.com/index.php/support/tools

Only the latest firmware 1.0.3.37 supports DHCP VLAN discovery. You may need to manually configure the VLAN.

The latest firmware 1.0.3.37 does not seem to be compatible with the current commercial FreePBX EPM.

Grandstream phones auto-reboot endlessly if they don't like the configuration files.

Try performing a factory reset if you experience provisioning problems.

Perform a factory reset after any firmware update.

Here is an initial phone boot from the perspective of the PBX (TFTP server) with the phone booting on data VLAN. The phone switches to voice VLAN because of the configuration file. It then gets a new IP on the voice VLAN:

[root@ppmpbx ~]# tail -f /var/log/messages

Aug 23 15:03:33 ppmpbx xinetd[28577]: START: tftp pid=24976 from=192.168.70.65
Aug 23 15:03:33 ppmpbx in.tftpd[24977]: RRQ from 192.168.70.65 filename cfg000b8270f741
Aug 23 15:03:34 ppmpbx in.tftpd[24978]: RRQ from 192.168.70.65 filename cfg000b8270f741.xml
Aug 23 15:03:34 ppmpbx in.tftpd[24979]: RRQ from 192.168.70.65 filename cfg.xml
Aug 23 15:03:35 ppmpbx dhcpd: DHCPDISCOVER from 00:0b:82:70:f7:41 via eth0
Aug 23 15:03:36 ppmpbx dhcpd: DHCPOFFER on 192.168.71.68 to 00:0b:82:70:f7:41 via eth0
Aug 23 15:03:36 ppmpbx dhcpd: DHCPREQUEST for 192.168.71.68 (192.168.71.30) from 00:0b:82:70:f7:41 via eth0
Aug 23 15:03:36 ppmpbx dhcpd: DHCPACK on 192.168.71.68 to 00:0b:82:70:f7:41 via eth0

This is a 'normal' phone reboot with phone already on the voice VLAN:

Aug 23 15:13:13 ppmpbx dhcpd: DHCPDISCOVER from 00:0b:82:70:f7:41 via eth0
Aug 23 15:13:14 ppmpbx dhcpd: DHCPOFFER on 192.168.71.68 to 00:0b:82:70:f7:41 via eth0
Aug 23 15:13:14 ppmpbx dhcpd: Wrote 5 leases to leases file.
Aug 23 15:13:14 ppmpbx dhcpd: DHCPREQUEST for 192.168.71.68 (192.168.71.30) from 00:0b:82:70:f7:41 via eth0
Aug 23 15:13:14 ppmpbx dhcpd: DHCPACK on 192.168.71.68 to 00:0b:82:70:f7:41 via eth0
Aug 23 15:13:41 ppmpbx in.tftpd[25386]: RRQ from 192.168.71.68 filename cfg000b8270f741
Aug 23 15:13:42 ppmpbx in.tftpd[25387]: RRQ from 192.168.71.68 filename cfg000b8270f741.xml
Aug 23 15:13:42 ppmpbx in.tftpd[25388]: RRQ from 192.168.71.68 filename cfg.xml
Aug 23 15:13:43 ppmpbx in.tftpd[25389]: RRQ from 192.168.71.68 filename /grandstream/1/gxv3275fw.bin
Aug 23 15:13:46 ppmpbx in.tftpd[25389]: tftpd: read(ack): Connection refused
Aug 23 15:13:47 ppmpbx in.tftpd[25390]: RRQ from 192.168.71.68 filename gxv3275cust

Phones auto reboot after requesting cfg.xml from the TFTP server when there are firmware compatibility, config file errors or provisioning problems.

To troubleshoot, you can manually edit the config file in a 'divide and conquer' method:

1. Make a backup of the problem file
2. Delete half of the file
3. Try it again

If you see Unfortunately, MPK has stopped., try another factory reset.

Insert a paper clip into the reset hole in the back of the phone. Press and hold for at least 7 seconds.