My voicemail does not work with my iPhone 7 Plus iOS 11(Wal-Mart Family Mobile)?

So my carrier is Wal-Mart Family Mobile, and I just recently bought a iPhone 7 Plus under T-Mobile with the iOS 11 update. Family mobile does not offer Visual Voicemail so I usually had to dial 1 to access my voicemail. But now since I got this new phone it says is not recognized, Please contact customer care…' I tried to access the Voicemail settings in the iPhone but for some reason it is not listed anywhere in my phone. I think it's because I don't have visual voicemail set up. Family mobile doesn't know how to fix the problem and I hope some one has the same issue as me and can direct me in the way to fix it

In Settings you have to set up your voicemail over again. Some thing we think would carry over from a previous phone, do not.
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I'm guessing the voice mail number got corrupted. Try dialing your number from your phone. It should take you to the VM. If it works you can program the phone number in settings to yours. You can also try calling them back and asking them what the VM number is supposed to be.