A single SMS message has a maximum size of 1120 bits. This is important because there are two types of character encodings, GSM and Unicode. Latin-based languages like English are GSM based encoding, which are 7 bits per character. This is where text messages typically get their 160 character per SMS limit. Long messages that exceed this limit are concatenated. They are split into smaller messages, which are recombined by the receiving phone.
With the strong growth in the use of smartphones, app usage has also greatly increased. Therefore, mobile marketers have increasingly taken advantage of smartphone apps as a marketing resource. Marketers aim to optimize the visibility of an app in a store, which will maximize the number of downloads. This practice is called App Store Optimization (ASO).
You will have a greater chance of gaining access to their mobile number by following these guidelines. You can collect their numbers using a sign-up sheet at your register, asking them when talking on the phone, allowing them to submit a form on your website, or by giving them a number that they can text to subscribe to your SMS messages. Whatever you do, keep a copy of their permission to market to them via SMS, if you run into problems you will be glad you did.