My phone number should be saved. Could you please look me up with my phone number?
My phone number is already in the system, so could you please look me up with my phone number?
ご質問ありがとうございます。
「[電話番号](https://eikaiwa.dmm.com/uknow/questions/34609/)で登録しているので、電話番号で受付をしてください」は英語で「My phone number should be saved. Could you please look me up with my phone number?」と言えます。
また、別の言い方で「My phone number is already in the system, so could you please look me up with my phone number?」でも言えます。
ご参考になれば幸いです。