Messaging service falls in Class 38, telecom, and depending on what exactly you sell it can also fall in Class 42 or Class 35 or Class 45. Everything below is read from the USPTO's own list of accepted descriptions, not from an opinion about where it belongs.
Searching the USPTO Trademark ID Manual for messaging service returns 30 accepted descriptions, and most of them sit in Class 38. The manual is the list of identifications the office has already approved, so wording taken from it is pre-approved and settles the class at the same time.
The class follows from the identification you write, so "what class am I in" is really "what exactly do you sell". How the class system works covers the rest.
Telecommunications like phone, internet access, or messaging services.
23 accepted descriptions in the manual mention messaging service. For example:
Software as a service (SaaS), app development, IT, design, or science and engineering services.
3 accepted descriptions in the manual mention messaging service. For example:
You run a store, sell advertising or marketing, or provide business and office services.
2 accepted descriptions in the manual mention messaging service. For example:
Legal, security, or personal and social services.
1 accepted description in the manual mention messaging service. For example:
Messaging service appears in 4 classes because what you make, what it is made of and the service of selling it are separate classes. Pick the descriptions above that match what you actually do.
Messaging service is a service, so it sits in Classes 35 to 45. Software that delivers a service is often Class 9 or Class 42 as well.
Telecommunications: the service of carrying messages and streams from one place to another. The devices it runs over are goods, so telephones are Class 9.
The class decides what a registration covers; it does not decide whether the name is available. Relatedness is judged on the identifications, so a conflict can sit in a class you never looked at: the same name in a different industry.
Check whether your name is clear for messaging service Searches the live USPTO register, including sound-alike and meaning-alike names. First search $2, then $5.Messaging service sits in Class 38, telecom. That is where the USPTO's own ID Manual puts it: 23 accepted descriptions mentioning messaging service fall in Class 38. Depending on exactly what you sell it can also fall in Class 42 or Class 35 or Class 45.
You file in every class you actually use the mark in, and the USPTO charges its fee per class. Selling a product and also running an online store for it is two classes, not one. Filing in classes you do not use is worse than filing in too few: an application has to be supported by real use or a genuine intent to use.
No. The class decides what a registration covers. Availability turns on whether someone already holds a similar mark for related goods, and relatedness is judged on what the identifications say rather than on the class number, so marks in different classes can still conflict.
Not what you sell? Search the class finder for your own wording, or browse all 45 classes.