Our techs' phones are on a personal plan nobody manages. Should that change?

The usual arrangement in a trades business: techs use their own phones, maybe with a stipend, and company email, the dispatch app and customer phone numbers all live on them. It works fine until somebody leaves.

What actually goes wrong:

• Company data walks out. Customer contacts, job history, photos of the work, the dispatch app with the full schedule. You cannot wipe the phone, you should not try, and the data stays.
• Your customers call the tech, not you. The number the customer has is the tech's personal cell. When they leave, sometimes for a competitor, that relationship goes with them, and this is a real commercial problem rather than an IT one.
• A lost phone is an open mailbox. If there is no passcode requirement and no way to revoke access, a phone left on a job site is a live session into your email.

There are two reasonable answers and they suit different businesses.

Keep personal phones, manage the work part. We set up the company email and apps inside a managed area of the phone. We can require a passcode and encryption for that area, and remove company data on departure without touching their photos or personal accounts. Most people accept this readily once it is explained that we cannot see their personal side, which we cannot. This is the lower cost route and it covers the main risks.

Company phones for the field. More expensive, and it solves the customer relationship problem as well, because the number belongs to the business. For a company where techs own customer relationships and turnover is a concern, the math often works out.

Either way, two things should be true: company email requires multi-factor authentication, and there is a written step in your exit process for removing access. That second one takes a minute and is skipped almost universally.