i am filing tax from overseas and only have an international phone number, however it only lets me use an american number when filling out my details. what should i do?

The IRS will not accept an international phone number for filling purposes. You will need to enter either a "dummy" US phone number, or a phone number from a relative or friend. 

See this previous response to a thread by @ToddL99

https://ttlc.intuit.com/community/tax-credits-deductions/discussion/i-do-not-have-a-u-s-phone-number-the-turbotax-program-does-not-accept-my-foreign-phone-number-in-its/00/2244650#:~:text=They%20will%20not,800%2D555%2D1212).