Send notify to URI

I’m trying to send a notify to a specific URI. The notify event I’m sending does work as I’m able to send it to an endpoint just fine. However, a certain endpoint can have more than one device and I want to be able to specify a specific contact.

I have found this post Pjsip send notify to a uri. I tried adding a random extension number to default_outbound_endpoint in pjsip_custom_post.conf. It doesn’t work. It only works if I set it to the extension number of the endpoint I’m trying to send the notify to.
Ex 1 : default_outbound_endpoint=200 : Doesn’t work sending a notify to uri sip:279@ipadr
Ex 2 : default_outbound_endpoint=279 : It will send the notify to the correct device with pjsip notify feature uri sip:279@ipadr

I have tried entering the URI different ways (with port, complete contact…) it doesn’t change anything and does work with sip:endpoint@ipadr.

So, obviously I don’t want to have to change the default_outbound_endpoint every time. How have you gotten this to work ?

I don’t fully understand how default_outbound_endpoint works and the asterisk documentation links have changed and I can’t seem to find better information to help me better understand my issue. Is anyone able to explain it to me or guide me in the right direction ?