At the moment, AppRealKit has just released the Multi-Player Game and Real-Time Application Cloud for Corona such as Photon Service but it is faster and _ cheaper _.
There is a free 365-days plan for all developers.
The detail at : http://apprealkit.com/sdk/corona.html
The client SDK : http://static.apprealkit.com/sdk/lua/ARK-Lua-SDK-V101.zip
It is simple to integrating the AppRealKit SDK into your Corona projects such as the image below.
Thanks !!!