There are a few ways,
Obviously you can always email / sms from ServiceM8, but this would have limited functionality.
The 2 preferred ways would be to either
- Add them as limited access staff members (more problematic & require iOS in field)
- Use the ServiceM8 Network Tool. This would allow you to send the key aspects of the job to the external agent, have the option to indicate what you need from them, as well as allow them send content directly back to you (such as a picture or document, even use your ServiceM8 Forms!).
Check out the referenced help doc, and do some testing to see if it will meet the need!