Swiss post has a similar thing, you can buy a stamp (on the form of a 9-letter code) via SMS. Never used but seems it works. No barcodes for regular stamps for

Swiss post has a similar thing, you can buy a stamp (on the form of a 9-letter code) via SMS. Never used but seems it works. No barcodes for regular stamps for now, but datamatrix barcodes are used since more than 15 years for bulk mail and print-at-home stamps.