Your guidance on better connections

Hello All,

I am using SMACK on Android with ejabberd as the backend.

After upgrade to 6.0 my app is not working as when in deep sleep mode data connection is blocked by android causing message delay.

I read about this on web and found using GCM for the same.

I wanted to check in the community is there any other way apart from GCM to get this working ? Is GCM reliable in this case of sending messages to offline peers ?

Any help on this will be really appreciated

Thanks.