Hi Kiran,
1. You need to maintained the host entry in hosts file on the both server
2. Also maintained the entry in services file.
3. you can check whether the port 4901 is used by some other application on dialog instance
4. Go to the below directory on CI server /usr/sap/<SID>/SYS/global/
and open the file ms_acl_info and make a entry
HOST= * and save the file
Please check the below sapnotes.
Note 1843686 - Upper/lowercase in the message server ACL file
Note 821875 - Security settings in the message server
With Regards
Ashutosh Chaturvedi