First : you should have SIP 3rd party license on system or you can try it with 60 days trial mode
Second : go to PCPro tool of SL1000 then filter options ==> IP phone list then select one ext number you will find it on command 15-05 select it and go to item 15-05-16 and give it authentication password upload unsaved data to the system then disconnect from PCPro

Third : then go to your mitel phone and give it the registrar server is your VOIPDP IP on command 10-12-09 with port 5070 and authentication password and reboot it i think it will connect to system and get internal dial tone



NEC Business Partner
Certified on SV8100,SV8500,SL1000