Help with Schematic-Trying to make a MODEM

Hello, I am trying to build a MODEM to communicate with my PIC. Please note that the modem is in a shape of a module, I am designing a PCB for it. I do not understand few terms though they may be very basic but I do not want to make any mistake as it will an expensive one. I am attaching a snapshot from the datasheet explaining about the voltages on the pins which I am going to connect to my PIC. Could you please advise me if I can connect these pins directly to my PIC or there is some sort of circuit needed between them.
Before you checkout the attachment please note that VDD_EXT=2.9V
Many Thanks

Could you please also tell me what VOL, VOH, VIH, VIL actually means and which ones are the one to look for next time I want to connect any device to my PIC. Thanks

VOH and VOL are the voltages you get when the device sets its output to High or Low. VIH and VIL are the voltages the device expects to interpret the value as a 1 or a 0.

For VDD_ext = 3V, you should ideally be using a PIC that can operate at 3V.

Thanks for replying. My PIC will be running on 4V actually. Will it be able to accept data with those outputs of between Gnd & 2.73V ?

If yes then I assume I can connect the module pins directly to the PIC without any amplifier circuit in between. Is that correct?