As iMessage is available on Android now, you will be able to cross-device chat with every contact who is using iMessage.
Send photos, videos, text messages, contact information or share locations from iPhone to Xperia Tablet and from iMac to Galaxy S5. It is free, as long as your device is connected to the internet. iMessage on Android will automatically check if your contact has iMessage installed. A blue send button indicates that you can send the message for free, a green button will indicate that iMessage Android switched to SMS or MMS.
If you are interested in trying iMessage Android, go to the download page.