Twilio now has subaccounts. You can now build multi-tenant web applications that use the Twilio Voice or SMS web services.
Now you can build a single app and create individual “subaccounts” for each customer you have. By segmenting users into subaccounts, you can track the usage of individual customers and provide individual customer billing.
Subaccounts can have their own account sids, phone numbers and caller IDs. You can also access subaccounts calls, SMS, recordings and transcriptions.