I created an app to send SMS, and works fine on the sandbox settings, but doesnt work when i change to production with proper clientid, client secret etc. It returns 'Invalid resource owner credentials' error.
Please read this article. Summary, you cannot send SMS on behalf of other extensions. The number must belong to the extension who currently login your app, and the number must have the SmsSender feature.
In your case, I guess that you are using the company number from an extension which is not assigned with the SmsSender feature. Check the sample code from the quick start link below to see how to detect SMS feature before using the number.
i managed to get working, but got another question, how can i use other phone numbers that have different extension as from number other than the main number under telus business connect user list to send sms
Please read this article. Summary, you cannot send SMS on behalf of other extensions. The number must belong to the extension who currently login your app, and the number must have the SmsSender feature.
In your case, I guess that you are using the company number from an extension which is not assigned with the SmsSender feature. Check the sample code from the quick start link below to see how to detect SMS feature before using the number.