Voice SMS.
In many part of the world Voice SMS is picking popularity where English alphabets are less used. With the Voice SMS people can send their voice with happy, sorrow, laughing, teasing, and many more emotions. So both parties don't need to understand the English Alphabet to Send and receive SMS with Voice. Because of this many countries in Asia where the rural population lack in English education use this facility.
You don't need to search for the letters to type SMS text message. Because of this Voice SMS is so popular in rural parts of the Pakistan, India, and Bangladesh. Recently in Bangladesh on the ID festival day mobile operators offered 20 free calls to their clients.
These Voice SMS are not so much expensive to make, and the users will like it for the convenient of the usage of the service. For example, in India, mobile operators have priced the services at a reasonable of 75 paise to Re 1, while their text SMS is priced at around 55 paise.
The state-run MTNL phone was the first telecom company in the world to launch Voice SMS on fixed line.