Any therapy conducted via telephone is not covered by insurance, unless of course the phone is being used as a platform for video using an app.
90837 is a "timed code" it does not signify that the visit took place in person. It absolutely cannot be used for phone therapy.
When submitting claims to insurance for teletherapy, you would use the appropriate timed code (90832, 90834, 90837), place of service 02 (telehealth) and a GT modifer.