ご用件がありましたら、電話でお願いします。って英語でなんて言うの？

Explanation: 'If need be..' means: in the event of their being a need.  A little more formal is sentence 2. However, to put such a message on social media in a non business sense seems a little over attentive from the western point of view Example sentence: "Please contact me should you require my assistance."

To 'feel free' is to have no restrictions placed on you. Telling someone to 'feel free to contact you' is to give them permission to get in touch with you anytime they like, and about any subject they want.

"For more information call me." this invites the person to call you if they want to. "Please call me if you have any questions or concerns." this tells the person that if they want to ask a question or they want to tell you something they should call you.

Please call me suggests that they call you on the phone if they want/need anything if you say 'please contact me' this might suggest other communication as well as a phone call so email/text etc

You can use phrases such as: "Don't hesitate to..." or "feel free to..." if you want to assure someone that they can contact you for anything at anytime.

All three of these sentences mean the same thing, that if the person wants to contact you then they should ring your phone. "Feel free to give me a call" is probably the most friendly and most informal out of all the sentences and would be appropriate online for social media. Whereas, "Please call me if you need anything." is more formal and more appropriate for letters.

If you want to say that someone must call you if they need to contact you, you can say: "Please call me if you need anything." "You are welcome to call me if you have any inquiries."