Hi, Draden.
For getting a list of phone numbers for Customers, using the PhoneNumber DBObject would be a safe bet. The methods get() and get_customer_phone_numbers() should do what you want.
Documentation: https://docs.q2developer.com/api_references/q2_sdk/db/db_objects/phone_number.html?highlight=phone#module-q2_sdk.hq.db.phone_number
There is, at the time of writing this, a confirmed bug with the Q2 AddChangeOfAddress API. Quoting Ryan Hollister, a senior engineer at Q2:
"We've identified a bug in Q2API AddChangeOfAddress that causes this error. It will need to be resolved in an HQ fix. Recommendation is to try the WedgeOnlineBanking version of AddChangeOfAddress: https://docs.q2developer.com/api_references/hq_api/wedge_online_banking/AddChangeOfAddress.html"