Apps Sending Message in Android Tablet PC using wifi

Hi Everyone!
I've done an Android Application that composed of many Edit text that can send message, seems no error I installed Application into Android Phone, and yet it can send message using SIM Card, and I also installed the application in Tablet PC, the problem is it can't send message coz there is no SIM Card Provider, can I still use this Application that can send message using WIFI in Tablet PC? or is there any solutions for this?

Thanks in Advance