When considering Optus Mobile services, it is important to be aware that some fees may not be immediately apparent. Typically, customers should examine the terms and conditions associated with their chosen plan or service. Charges such as establishment fees, monthly plan fees, and excess data charges can sometimes catch customers off guard. Additionally, there may be fees for international calls or texts, as well as potential charges for using services while roaming. Equipment costs, like those for smartphones or accessories, can also add to the total expense. It is advisable for customers to thoroughly review the details provided on the Optus website concerning their specific plan, as this will give the most accurate and comprehensive information about any potential hidden fees that may apply.