In Sender ID field, you can see a drop down to select your preferred sender ID.
Selected Sender ID will appear as senders address in recipient mobile.
If your account is enabled for Open Sender ID, you may see a text box instead of drop down and you can use any dynamic alphanumeric sender ID.
Max recommended length of alpha numeric sender ID is 11 characters and 15 digits for numeric sender ID (AlphaNumericSender ID is not allowed for Nigeria Networks)
NB: In certain Countries, You will have to Register your Sender IDs before sending SMS else Messages will not be Delivered By Operator. Registration is free and Usually takes about 2 business days.
NB: SENDER ID REGISTRATION IS MANDATORY FOR NIGERIA TRAFFIC