Open The Truly Mobile app on iOS
Navigate to the 'Contacts' tab and press the '+' in the top right corner to start creating a contact.
Enter the Contact information, which can include Name, Position, Company, Phone Number and Email and then select 'Done' in the top right.
Refresh the contacts page by viewing another page, and you will now be able to see your contact.
Contacts will be viewable inside the call list and conversation views, as well as on SMS threads. Contacts are not currently supported for Group SMS threads.