Add endpoint guide for FRITZ!Box 7390

docs/guides/endpoints/hardphones/fritzbox-7390.md

@@ -0,0 +1,44 @@
+# FRITZ!Box 7390
+
+The [FRITZ!Box WLAN
+7390](assets.avm.de/files/docs/fritzbox/fritzbox-7390/fritzbox-7390_man_en_GB.pdf)
+is a (EoL) router with [built-in telephony
+support](http://service.avm.de/help/en/FRITZ-Box-7390-avme/016/hilfe_fon_anrufliste).
+
+Configuring a HoIP account in its PBX allows you to then use any other telephony
+device (POTS, DECT, SIP phones, ...) to use and react to it, with a Preselection
+prefix if desired.
+
+## Configuration
+
+1. From the main admin page (generally at http://fritz.box), open the
+   “Telephony” menu in the left sidebar, then select “Telephone numbers”.
+2. In the telephone  numbers page, choose the “New telephone number” button at
+   the bottom right of the list.
+
+![Screenshot of the FRITZ!Box Telephony admin page for Telephone Numbers](./images/fritzbox-7390-telephony-numbers.png)
+
+3. Fill out the form as follows
+
+3.1 Set the “Telephony Provider” dropdown to “Other provider”; If you want to
+later add additional HoIP extensions, you can select the existing provider
+instead.
+
+3.2 Set the “Telephone Number for Registration” and “User name” to your
+Username/Extension from the registration email. You may also want to set
+“Internal Telephone Number in the FRITZ!Box” to the same value.
+
+3.3 Set the “Password” to the Password from the email.
+
+3.4 Set the “Registrar” and “Proxy server” to `<SERVER>:<PORT>`
+
+![Screenshot of the FRITZ!Box admin page, setting up a HoIP account](./images/fritzbox-7390-add-number.png)
+
+4. If all goes well, the next page will test the connection and succeed.
+
+5. Back to the Telephony admin page, you can see the green light next to the
+   account, confirming that it's functional. You can also use the pen icon to
+   edit a few more parameters for the account, but nothing that should be required
+   for it to work.
+
+!!! note "Last updated 2025-10-26 Olivier VK7SHM"

docs/guides/endpoints/hardphones/index.md

@@ -20,6 +20,10 @@ We have the following Guides available now:
 
 * [X210/X210-V2](./fanvil-x210.md)
 
+# FRITZ!Box
+
+* [7390](./fritzbox-7390.md)
+
 ## Grandstream
 
 * [GXP16xx Series](./grandstream-gxp16xx.md)