Mobile phones can be had on working days. That can be grammatical, but it is not clear what the sentence means. We can answer your question better if you tell us why you are asking. If you read this sentence somewhere, where did you read it? If you want to write or say something, what do you want to say?

There's nothing wrong with the grammar. It's grammatically OK to use 'can' + 'be' + a past participle. It's a standard modal passive. The problem is with the choice of verb. It wouldn't be normal to use "had" in this context : it's too vague and also too informal. "Application forms can be obtained" would be better.

I suggest that you edit the question to include the context "admission forms can be had in the office". "Can be had" can mean a number of things, including "can be tricked" and "romantically or sexually 'obtainable'/available".

Mobile-phones can be had on working days.

Hey there This sentence is not correct, mostly because of a lack of information. It looks to me like the very first part is missing.