Voicemail setup W52p and changing the voicemail access code

Hello I have been slowly learning FreePBX and with the help of the reference material and have gotten it running with 2 Yealink W52p cordless IP phones and a SIP trunk with 2 channels. We would like to enable voicemail but have the mailbox shared between the two phones/extensions. Phone 1 is on extension 5000 and phone 2 is on 5001. I have read that I can create a virtual extension which i have done on extension 199 to try. I have enabled voicemail on this extension, setup a ring group and set the ring group to go to the voicemail at extension 199 when busy.

I am now a little stuck in how I can configure the voicemail button (1) to call the 199 mailbox. At some point we may also need to look at making the message indicator light work for new voicemail arriving at the 199 mailbox.

I have tried holding 1 but it says voicemail not setup. If I call *98199 I do get through to a mailbox. Going into settings on the handset and selecting line 5001 for example, states that voicemail is not setup - although I know that i don’t want it to go to 5001’s mailbox anyway.

I’m obviously missing something. How do i configure the phone handsets so that they are able to quickly dial the shared mailbox 199, from button 1 if possible. If anyone has time id appreciate some guidance on how to make the message indicator light work too if anyone has knowledge of this phone model.

Many thanks,
James.