I guess reading my entire post was too complicated.
Copied from my first post, which you apparently missed or don't understand.
Ask the sender of an MMS to address the MMS to an email address for an email account that you access with the iPhone's mail client instead of your cell phone number with area code. You will recieve the MMS as an email with the photo as an email attachment.
I don't exchange MMS often - I leave that to the kiddies, but I do on occasion with a niece who is a high school kid. She is a Verizon subscriber. She addresses the MMS to an email address for an email account that I access with the iPhone's mail client, and I receive the MMS as an email with the photo as an email attachment. Since I access the email account with an email client on my computer, I also have access to the received message and photo attachment on my computer also.
This gave me her cell phone's MMS email address. I added this email address to her contact info. I select a photo to be sent as an email attachment and when addressing the email to her cell phone MMS email address, she receives the email and photo attached as an MMS.