If, after moving to an Iphone from Android, you are getting gibberish text messages on your Iphone when you receive phone calls that go to voice mail (i.e., messages that start with "VZWVVW" ) do the following:
1. call tech support at *611 and tell them your getting text message gibberish when you get notifications of voice mail
2. then tell them the way to fix it is to do an "internal refresh of the mailbox." This is what has worked for me and I hope works for you.
A possible idea that may work to avoid this: if you initially switch from an Iphone to an Android, with the Android device off, disable both Messaging and Facetime on the Iphone (find under Settings). Then turn off Iphone before moving the SIM to the Android phone, then power up Android phone.
Then if you move back to Iphone from Android, hopefully the gibberish text messages will not appear again. Note power off both devices before moving SIM card from the Android to the Iphone, then restart Iphone after SIM card installed. Good idea to not move SIM cards without powering off the devices prior to moving.