iPhone "Cannot Connect to Voicemail"
My wife's iPhone 4 came new out of the box at the telecom store. Neither of us have visual voice mail, in which case the voice mail button should just display a list with voice messages. It works on my phone, but it did not on my wife's. Instead, it displayed an error:
It simply asked to contact Telus Mobility for assistance. I did. At first they wanted to sell me their visual voicemail feature at $7/mo. When I explained that it works on my phone, they just made me Google it. Wow. Then they had me reset her voicemail password, which some folks reported as the solution in various forums, but that didn't work for us.
What did work is the following:
From the keypad, type *5005*86*-----------# where the dashes represent your 11-digit voice mail number (typically starting with 1). Then tap call. The screen will flash, ever so briefly, and after that it looks like nothing happened. (It doesn't actually make an outbound call.) Clear the number off the screen (switch to favorites and back or something) and press and hold the 1 key. It dialed voice mail! From then on, the voice mail button also started working.
Mind you, I know that we dial our own number to access voicemail. If your service provider has a fixed number (as many do) you would have to enter that number. This option seems to reprogram the voice mail number to what you enter.
The code *#5005*86# displays the currently active number.
Disclaimer: This worked for me. It may not work for you. If in doubt, please contact your service provider. As always with anything you find on the internet, use at your own risk.
This is still valid for the iPhone 7.