hello
my clients have softphones can they talk localy using MK . if yes guide me how to ?
Well the “talking” wont go through mikrotik but rather through the switch - mikrotik simply provides the routing information necessary for communication to commence.
Regards.
(Once they are in the same same network i.e. /24 they should be able to use the sip protocol without problem.)
Just point your local sip clients to the sip server and make sure you set the registration port to 5061 (standard) and make sure the firewall on your computer(s) permit udp traffic from ports 10000-60000. (it varies)
Regards
Edit *** Guess I misunderstood the question 
Mikrotik itself it not a sip server, for that purpose youd wanna try Asterisk … Google and ye shall find.