Please create the possibility to customize your own provider for Dynamic DNS.
Many providers today offer the possibility to operate dynamic DNS with their own domain via an update URL or API. So you are no longer dependent on services like Dyndns.
My wish would be to define a new entry next to the known providers, which could then be called e.g. user defined.
A possible schema for calling an update URL could look like this: https://www.provider.com/dnsupdate/update.php?username=<username>&pass=<pass>&hostname=<domain>&ipaddr=<ipaddr>
Where the IP address is a variable, which is then replaced by the PBX with the external IP.