A facility used for impressing pre-paid postage rate on letters is called?

The facility used for impressing pre-paid postage rate on letters is called a franking machine. It is a device that prints a special mark or stamp on the envelope or package to show that the postage has been paid in advance. The franking machine is commonly used by businesses and organizations that send a large volume of mail on a regular basis. It helps them save time and money by automating the process of stamping and processing mail. The machine calculates the correct postage rate based on the weight and size of the mail and prints the mark or stamp accordingly. This allows the sender to avoid the hassle of buying stamps and affixing them to each piece of mail individually.