How to send a graphic in a text message to a smartphone? (Likely using Twilio)

I have used SendMessage["MMS"…. to send text with graphics to my mobile phone number given at $MobilePhone. But I would like to send MMS messages to other phones as well.
I’ve sent text using the Twilio service using:

  twilio = ServiceConnect["Twilio"];
  twilio["Send", {"To" -> "##########", "From" -> "(xxx) ###-####", 
  "Body" -> "Text in the message body including calculations like "<>ToString[answer]<>"."}]

Where I’ve redacted private phone numbers by replacing digits with ###’s.

But I would like to include plots that have been created in the code.
I can follow the example and include a graphic from a web URL using, for example:

ServiceExecute["Twilio", "Send", {"To" -> "##########", 
  "From" -> "(###) ###-####", 
  "Body" -> "This was sent from the Wolfram Language", 
  "MediaURL" -> 
   "https://content.wolfram.com/uploads/sites/10/2019/04/Thumb_
Mathematica12.png"}]

But how do I include a local graphic that has not been uploaded to the web? I am looking for something like "Media" rather than "MediaURL."
Thank you in advance for any help,
Steve