Advice Mary Wakio why she should not use telex to communicate to her friends

Her friends may be illiterate and may be unable to read the message received
Her friends may not have a receiving machine and will be unable to get the information
It can be expensive to use as the sender pays a subscription fee and rental fee while he and the recipient pays for the sent message
It can be expensive to buy the teleprinters used in receiving and sending information
Telex may only send written messages but cannot be used to send maps, diagrams and charts