Integrating SIP with Simplex 5100 PA System

[Stewart1 (Stewart)]

One approach:
Set up a pjsip trunk with Registration: Receive and set up the HT FXO to register to the PBX.

FreePBX and Grandstream HT813

Hey, I work in IT and wanted to start a home project, where I set up a phone system and replace my analogue telephones with IP phones. I have so far, managed to achieve this to an extent, but having some trouble getting the FXS port on the Grandstream HT813 to register a SIP extension on my install of FreePBX. I have one pjsip trunk which routes calls from VOIP to the FXO port on the Grandstream HT813. If I disable this trunk, the FXS port will successfully register and I can then call the ext…

may be useful; you can find other guides online.

Using # in called numbers is often problematic, so I suggest that you set your Outbound Route to rewrite some numeric string to #10. For example:
prepend: #10
prefix: 7243
match pattern: (blank)
CallerID: (blank)

Also, set the Dial Plan for the FXO port in the HT to permit #10 to be dialed.
Then, when the user dials 7243 (PAGE), the PBX will send #10 on the trunk and with luck the 5100 will respond.

If you still have trouble, paste the Asterisk log (with pjsip logger on) at pastebin.com and post the link here. If the HT fails to register, paste the log for a registration attempt. Otherwise, paste the log for a call to 7243 (or whatever else you use to trigger the page).