If you have a Google Voice number, you can click any phone number in Myphoner and the call is placed through Google Voice in your browser. This uses Google Voice's own one-click dialing feature, so there's nothing to install.
Prerequisites
A Google Voice number.
A computer with Google Chrome, Microsoft Edge or Mozilla Firefox. One-click dialing doesn't work on phones or tablets.
Step 1: Turn on one-click dialing in Google Voice
One-click dialing lets Google Voice handle phone number links in your browser. Follow Google's guide to turn it on: Use one-click dialing on Google Voice.
In short, you open Google Voice on your computer, register for one-click dialing, and click Allow (Chrome and Edge) or Add Application (Firefox) when your browser asks. Google's guide also shows how to check that it's switched on.
Step 2: Set your Dialler to "Other/tel protocol"
In Myphoner, go to My Preferences > Dialling.
Set Dialler to Other/tel protocol.
Leave Use Country Codes turned on. Numbers are then sent to Google Voice in full international format (e.g. +1 706 406 5608), which avoids calls going to the wrong country.
Phone numbers in Myphoner are now links. Clicking one opens Google Voice and places the call.
Troubleshooting
Clicking a number doesn't open Google Voice. One-click dialing isn't switched on in this browser, or another app is handling phone links. Use the "check it's on" steps in Google's guide to make sure voice.google.com is listed as the handler for phone ("tel") links.
Phone numbers aren't clickable at all. Check that your Dialler isn't set to None. That option shows numbers as plain text and turns off click-to-call.
Fallback: open Google Voice with a custom link (US and Canada only)
If you can't get one-click dialing to work, for example because your browser never shows the prompt or your company computer doesn't allow it, you can have Myphoner open Google Voice directly instead:
Go to My Preferences > Dialling.
Set Dialler to Other/custom.
Paste this into Custom VOIP link, exactly as shown:
https://voice.google.com/u/0/calls?a=nc,%2B1{{value}}Turn Use Country Codes off. The link already adds the +1 country code.
Clicking a phone number then opens Google Voice in a browser tab with the number ready to call.
Please note: this uses the call link format from Google's guide Make a call with Google Voice. Because the link adds +1 for you, it only works for US and Canadian numbers. Use one-click dialing (above) whenever you can.
The Google Voice and Google Hangouts browser extensions that older guides mention have been discontinued by Google and are no longer needed.