Two numbers

[Tater3699]

I switched yesterday from tmobile. I wanted a new number and it gave me a 220# but the old number is still connected and I have a private number and a travel number which are the new and old number. I am still getting messages on the old number and I have an iPhone but my messages are green on the new number? Help! 

[upstate-SC]

iPhone uses Messages app for handling SMS (cellular service based) as well as iMessage (Apple's proprietary technology).

If you were using iPhone, then the mobile number is registered for the iMessage service by Apple. So any iPhone users who use Messages app (default app in iPhone by the way) to send you a text message it prefers iMessage service (blue bubble) by Apple to send, only if it is unable to connect to internet it retries to send in SMS (green bubble).

If I understand from your wording, your old number is still registered with iMessage try to deregister it and add new number to the iMessage.

References: 

https://selfsolve.apple.com/deregister-imessage/

https://www.verizon.com/support/knowledge-base-104603/

https://support.apple.com/en-us/HT203042