The Sender ID for an SMS message acts like the ‘return address’. When a recipient replies to a message from their handset, it will be sent to the particular Sender ID that was used to send the message. This means that for someone to be able to reply, there must be a valid numeric Sender ID used.
If you use an alphanumeric Sender ID (A custom word), recipients will not be able to reply back to your message. However, this sender ID is perfect for one way messaging.
If you use your personal mobile number (Verified Number), replies will go to your mobile handset directly and not pass through SMSGlobal (only supported for Australia).
Using a virtual dedicated number is the best Sender ID option to ensure replies are received back.
If you use SMSGlobal Shared numbers, replies from recipients can be received for 48 hours after the initial outbound message has been sent.
For more information on Sender ID's please refer to the other articles in section Sender ID.