What does the marketing SMS mean by the number of people who check in?

it means to urge customers to book hotels by sending marketing short messages, and count the number of people who finally stay. "Marketing SMS" is the marketing means of hotel service industry. "caliber" means statistics, and this caliber is usually one of the important indicators for hotel marketing departments to measure the effect of marketing activities. So this sentence means that by sending marketing messages, customers are urged to book hotels, and the number of people who finally stay is counted, so as to judge the effect of the hotel marketing department in measuring market activities.