First of all 'static' and 'object' really makes little sense.
Any static class cannot be instantiated. So you cannot create a static instance object of a normal class.
If you define your class as static
e.g.
static class ReceiveMsgService()
you will be able to direcly access static members inside the other class.
Otherwise the only option you have is to create an instance -
ReceiveMsgService o = new ReceiveMsgService();
and then use it accordingly.