# Useful Twilio Links 1. **Where can I find more information on Twilio's direct invoicing billing method?** Read [here](https://support.twilio.com/hc/en-us/articles/360025603913-Reading-your-Twilio-Invoice) for more on invoicing. Read [here](https://support.twilio.com/hc/en-us/articles/360022561474-How-to-Read-the-Twilio-Invoice-CSV-Supplement) for more on the CSV supplement provided for the invoicing method. 2. **Twilio asked me for my message SID. What is this?** This message SID is not the same as the messaging service SID which you obtained during the set-up process. This is an identifier for the SMSes that you have sent out, which provides Twilio with more information about your message such as delivery status, message content, and relevant timings. It is a 34 character string that starts with “SM…” for text messages. You can read more about it and find it [here](https://support.twilio.com/hc/en-us/articles/223134387-What-is-a-Message-SID-). 3. **How can I create subaccounts for my agency?** Some agencies prefer creating subaccounts for better accountability of message sending, or for governance within departments in the agency. Find out how you can do so [here](https://support.twilio.com/hc/en-us/articles/360011348693-View-and-Create-New-Twilio-Subaccounts). 4. **Does Twilio store my data (e.g. recipient mobile numbers, SMS message content) anywhere?** Data Retention, as well as deletion is covered [here](https://support.twilio.com/hc/en-us/articles/4410585868443-Data-Retention-and-Deletion-in-Twilio-Products). 5. **Can I find out more about what Twilio error codes mean?** Yes, Twilio documents them [here](https://www.twilio.com/docs/api/errors). --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://postman-v1.guides.gov.sg/campaign-guide-sms/sms/useful-twilio-links.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.