Contact Authorization Belongs to Backend Policy, Not Dialing Logic
SIP addresses endpoints; the product still needs an explicit policy for who is allowed to contact whom.
backend
Why the Backend and PBX Need an Adapter Boundary
Identity and parental policy should not be embedded inside SIP routing rules.
Parent-Approved Contacts Are an Architecture Rule, Not a UI Filter
Contact approval has to be enforced by backend identity and call routing, not only hidden buttons.
A Device SIP Account Should Be Rotatable Without Reflashing Firmware
Telephony credentials are runtime configuration, not compiled product identity.
QR Pairing Should Bind a Physical Device to a Backend Identity
Scanning a code is useful only if the backend can prove which unit and account the ceremony joins.
Backend-Delivered SIP Configuration Keeps Secrets Out of Factory Images
Per-device PBX credentials should be provisioned after identity is established, not cloned into every unit.
The PBX Adapter Keeps Product Identity Out of Dialplan Files
Asterisk should route calls, not become the only database of parent-approved relationships.
The Edge Voice Device Architecture Finally Connected Firmware, SIP and Backend Work
By the end of the year the interesting problem was no longer a codec or PBX; it was the boundary between device identity, firmware, SIP and backend control.
Blocked Has to Override Normal Device Behaviour
A backend revocation is ineffective if the device keeps registering and calling because local state still says active.