Many trademarks made up of letters only are known to the public as such, but it is often the case that this same public has never actually known the meaning of these initials.
What's more, most of these marks can only exist in acronymic form, since their meaning in extenso is so devoid of distinctiveness: such marks could not therefore be registered in their extensive form as trademarks before the competent offices.
So, 
which means Society Francade of Radiotelephone" could not have been accepted in its developed form. Indeed, it's hard to make it more descriptive. SFR is more distinctive!
Learn more about the distinctiveness of trademarks.
Examples of acronym brands
Here are some examples of well-known brands and their meanings:
International Business Machines. This is a good example of a trademark that could not have been registered as such, because it is so descriptive, and in any case it takes too long to pronounce... IBM is immediately simpler.
Hennes & Mauritz. Here we have an example of a brand that simply uses the initials of the company's founders. Note that even in its extensive form it would have been distinctive.
These are the initials of the founder's name, followed by the initials of his parents' farm and his village: Ingvar Kamprad, Elmtaryd, Agunnaryd.
In the same spirit as IKEA, these are the first letters in the name of the brand's creator and its city of origin: Hans Riegel Bonn.
British Petroleum. Here, a beautiful combination between the company's origin and the product it exploits. To banish, then!
Bayerische Motoren Werke. Same problem as BP.
Kentucky Fried Chicken. This one, apart from being descriptive, would even be frankly disappointing in its long version since it's very unlikely that the chicken consumed in the brand's French fast food restaurants comes from Kentucky (which is probably not bad, by the way).
Hngo Kong & Shanghai Banking Corporation. It is in fact, as its name does not indicate, an English banking group.
Another example of a brand simply made up of the initials of the founders: Adrian DAlsey, Larry. Hillblom and Robert Lynn.
These are the initials of Mars and Murrie, the founders of the company called M&M's Chocolate Candies. The brand now belongs to the Mars Incorporated Group.
Fabbrica Italiana Automobili Torino. The name speaks for itself, which is reason enough to use the initials.
Registering a trademark as an acronym: yes, but be careful!
If you're looking for a strong brand, it might be worth considering an acronym. But be careful:
- Don't register the acronym followed by the developed form: the INPI may refuse your trademark for lack of distinctiveness. As mentioned above for SFR, the developed form could make your trademark descriptive and lead to its refusal.
- Acronyms that are "well-known" to the general public should of course not be registered. For example, you can't register the acronym "DRH" for human resources departments, or the letters "UV" for sun protection. These terms must remain available to all market players.
Finally, it is interesting to note that some acronym brands have lost their distinctiveness: 
(which comes from the Soiété des Papiers-Linges) was unlucky! Initially, the trademark created in 1948 was descriptive only in its long version. Today, however, it has become descriptive in its acronymic version, since everyone uses this trademark as a generic term for paper towels. But : the original brand continues to exist and to defend its rights - so it's important to talk about "the SOPALIN brand". Ⓡ " !
If you are interested in this question : read our article on brand degeneration (how a brand becomes a common name).
Updated: 05/28/2023