Hi Lotam
Sorry for only comming back to me.
We did find a workaround (can’t remember what it was, but i think it was a timing issue)
I completely forgot about this post. 
The WS6318 is a very nice module, i like it alot.
But if I could suggest 1 change on a future release.
why not have 2 uarts on it, there is more than enough pins to use.
most telemetry users use gprs.
now you have to break connection check for incomming sms’s and then go back to gprs/ tcp socket mode.
it makes for much more complicated code.
so if there was 2nd uart it would make evrything much easier.
I would change all my designs to this module if there was 2 uarts on it
Or if you had cmux driver for me that I can place in my micro controller (I know your modules can do it, but to implement it is a different story)
I am willing to pay for such a driver.(if anybody can sell me such a driver then please PM me)
Thanks
Walter