@PiLYo1 

Hey

Sadly I cant see this working for you, its not possible to pass a telephone signal down via network hardware (switches and router).   You can use a cat5 cable to directly patch a telephone line, but not in the way you have anticipated with both signals going through hardware.

Would a dual handset wireless DECT phone work for you?  Have the base station at the router and the 2nd handset where you need it?   Usually cordless phones have a really good range due to the low bandwidth requirements.

  @Philbert Thanks for the suggestion of the wireless phones. That will work.

OPTION 1:

As of th moment, I have been researching. What I could do is split the CAT5e wire from the switch to the EAP225-Wall to make 100mbps connection and use the unused twisted pair to use for the landline. Since the max uplink port of eap225-wall is 10/100mbps, I would be having 2 twisted pairs that are unused, I can just use the brown line for the phone line.

OPTION 2:

I was also thinking if Its possible setup another WAN port  at the Gateway a VLAN dedicated to the phoneline and assign a specific port at the EAP225-Wall to use the same VLAN assignment for the phoneline using RJ45. What do you think?  

  @PiLYo1 

KJK is correct, it's not possible to push a telephony signal along the same cable as a data signal.    Yes you could do some fancy jiggery with the individual colours, but soon as you plug this into a network switch it will kill any telephony traffic.

The switch can only encapsulate network traffic, namely TCP IP packets.  It wouldn't know what to do with the signals from an analogue telephone and would at best just ignore this and at worst, damage the switch.

Option 1 would remove the POE from the equation, the AP would likely not power on.

Option 2, the switch / router wouldnt know how to encapsulate the data from the telephone and would likely lock out the port (as mentioned earlier)

Sorry, honestly dont think this solution is going to work for you.

  @Philbert Thanks. for this. I fully understand. I might just have to purchase a powerline to be able to addres this issue. Thanks for the help guys!