What is the Native Content URI for SMS Drafts?
Content Provider URI for SMS is commonly
   content://sms/...
and for SMS Drafts it is
   content://sms/drafts/
    You can open each SMS message part by opening different ways.
- Inbox = 
"content://sms/inbox" - Failed = 
"content://sms/failed" - Queued = 
"content://sms/queued" - Sent = 
"content://sms/sent" - Draft = 
"content://sms/draft" - Outbox = 
"content://sms/outbox" - Undelivered = 
"content://sms/undelivered" - All = 
"content://sms/all" - Conversations = 
"content://sms/conversations". 
来源:https://stackoverflow.com/questions/10453385/what-is-the-uri-for-sms-draft-content-provider