Update subscription API contracts

[tejaskh3]

Issue Description

The issue is we were using phone in "KEYS_NOT_ALLOWED" but while taking user phone inputs we took phoneNumber as field, which exposed phone number publicly.

Severity/Priority

• Critical
• High
• Medium
• Low

Additional Information

Checklist

• I have read and followed the project's code of conduct.
• I have searched for similar issues before creating this one.
• I have provided all the necessary information to understand and reproduce the issue.
• I am willing to contribute to the resolution of this issue.