https://devzone.nordicsemi.com/f/nordic-q-a/87427/how-to-acknowledge-on-a-received-opcode-from-respective-server-handlerHi, My BLE-Mesh client model sends an opcode to retrieve the server model state, When server model receives the opcode, relevant handler gets triggered from where I need to acknowledge or send the server state to client. Below handler I referreden-USTelligent Community 13Fri, 06 May 2022 08:12:26 GMThttps://devzone.nordicsemi.com/thread/366621?ContentTypeID=1Fri, 06 May 2022 08:12:26 GMT137ad170-7792-4731-bb38-c0d22fbe4515:b488eac0-3d52-4c44-b702-a99c35d551b3Mttrinh<p>Hi,</p> [quote user=""] in my case I do not have an addr[/quote] <p><span>What do you mean you you don&#39;t have an address?</span></p> [quote user=""] I am supposed to reply the state to the provisioning device, which is a mobile app.[/quote] <p>What mobile app are you referring to here? Are you using nRF Mesh?</p> <p>Since you are using a phone to provision, you can always set an address to the provisioner in the provisioner settings. An address is needed to send config messages or other messages than provisioning messages.</p><div style="clear:both;"></div>