OK then ,
change your micollab.mycompagny.local to micollab.mycompagny.com.
in the DNS entries, make the association between the ip of your micollab and the new fqdn.
where it is more complicated / to test:
1- quit the Micollab client and reconnect, if it works all the better otherwise:
you have to relaunch the client installation wizard to change the fqdn of your micollab to .com instead of .local ( you can do that with GPO if you have many users)
2 you can also go to c/program files x86 / Mitel /unfied communicator advanced 7.3 / UCA.exe.config then change the value = micollab.mycompagny.local by .com
this configuration is valid in lan mode only.