we are still using elastix 1.1-7 and a mix of grandstream phones. one gxp2020, one gxp2010, three gxp2000, and two bt200. All the gxp series phones have BLF feature and i have them activated but after probably 6 hours they stop working. They no longer show if that extension is busy like its timed out from the server or its not recieving a response anymore. Does anybody know how to fix this?