We have provided a sample invitation letter for inviting relatives and friends above. You may fill out the highlighted sections using your own information.Get your invitation later and network with experts. Please make sure the passport is no older than 10 years and has at least two blank pages to affix the visa;. 4. Additionally, we expect that you will be involved in activities that will allow for cultural exchange among faculty, staff, students and the Houston community. To obtain an Official Letter of Invitation for your visa process, please complete the form below. Information for international attendees of OTC 2025. Find visa and travel information, tips for navigating the conference, and networking opportunities. Invitation Letter Process: To request an invitation letter, you must complete your event registration. Be an author of an accepted submission (oral presentation, poster presentation, panel member); Have paid the registration fee, in full, for this conference.