Confusion in using comm.GMSKMmodulator and comm.GMSKDemodulator

At transmitter side, I take binary data, make it NRZ, pass it through a Gaussian Lowpass filter, integrate it and hence I get the integrated waveform which gives phase transition information. I then take cosine and sine of this integrated phase and then multiply these two components with cosine and sine of a signal generated, assuming it a local oscillator, at a frequency, lets say, 100K respectively. The resulting two components are what I send in parallel to the receiver.

At the receiver, in the absence of any channel, I multiply the same quadrature components from LO at the transmitter with the received quadrature components. I lowpass these components to limit their bands and then take arctan of these two to get the phase. I unwrap the phase, remove the latency caused by filtering and then convert the received NRZ signal to binary data. Using Viterbi decoder, the original binary data is retrieved.

How can I do this using the comm.GMSKModulator and comm.GMSKDemodulator?

At the transmitter, output of comm.GMSKModulator has to be considered the phase, right? Will I have to take its integral explicitly? Or It doesn't need the integration? How can I get phase transition information over the time here?

At the receiver, will I have to lowpass the components and then pass the resulting signal to comm.GMSKDemodulator? If integral has to be taken explicitly at the transmitter side, I'll have to take the derivative and then pass the resulting signal to the comm.GMSKDemodulator?