anchor.diff:            may be served via HTTPS.
           '';
         };
  +
  +      defaultPhoneRegion = mkOption {
  +        default = null;
  +        type = types.nullOr types.str;
  +        example = "DE";
  +        description = ''
  +          <warning>
  +           <para>This option exists since Nextcloud 21! If older versions are used,
  +            this will throw an eval-error!</para>
  +          </warning>
  +
  +          <link xlink:href="https://www.iso.org/iso-3166-country-codes.html">ISO 3611-1</link>
  +          country codes for automatic phone-number detection without a country code.
  +
  +          With e.g. <literal>DE</literal> set, the <literal>+49</literal> can be omitted for
  +          phone-numbers.
  +        '';
  +      };
       };
   
       caching = {
  
positive.code:         { assertion = ((acfg.adminpass != null || acfg.adminpassFile != null)
              && !(acfg.adminpass != null && acfg.adminpassFile != null));
            message = "Please specify exactly one of adminpass or adminpassFile";
          }
        ];
  
  
negative.code:               'dbtype' => '${c.dbtype}',
                'trusted_domains' => ${writePhpArrary ([ cfg.hostName ] ++ c.extraTrustedDomains)},
                'trusted_proxies' => ${writePhpArrary (c.trustedProxies)},
                ${optionalString (c.defaultPhoneRegion != null) "'default_phone_region' => '${c.defaultPhoneRegion}',"}
              ];
            '';
            occInstallCmd = let
  