Add voicemail

Hi @bjlockie
The only option is modifying your plan and wait the following month to get it
They don't have any add on

Or
You can have an app such Fongo and transfer the calls to that number when you don't answer https://fizz.ca/en/faq/how-do-i-set-up-call-forwarding

So create a new plan and port my number to it?

No. You don't want to create a new plan. You can change your existing plan for a new plan that includes voicemail. However, this will only become effective at the start of the next billing cycle and you can only choose from plans currently being offered by Fizz. https://zone.fizz.ca/dce/customer-ui-prod/account/plan -> Manage my plan -> Change my plan

Also, if current Fizz plans are considerably more expensive as compared to what you have right now, I'd seriously consider @elena code xzi4t 's second suggestion. Especially, if your intended use of voicemail is temporary. Who says that your voicemail service has to come from the same operator as your cell number? You can easily and temporarily forward your Fizz number to a 3rd party voicemail provider.

The FAQ says:

Only outgoing calls are possible when call forwarding is activated. Your phone will not ring and you will not receive any notifications (message, missed call, etc.). All incoming calls will be automatically forwarded to the programmed number until the call forwarding function is disabled.

This is contradicted later.
It also says you need a VoLTE phone.

It is not exactly a contradiction, just imprecise. The original "simple" implementation on how to setup call forwards will go by the wayside once 3G is being removed. LTE and 5G networks only support setting call forwarding and other supplementary services only over IMS registration. Which incidentially is also what provides VoLTE functionality.

What if you are in an area where there is no signal or the phone is off?

That's what the "subscriber is not available" setting is for.

Will forwarding still work if my Fizz phone is out of the area it works (still Canada)?

I haven't tested this on Fizz, but in general, if you don't actually want to receive calls when outside your coverage area, I recommend turning on the unconditional call forward (*21). Otherwise, you run the risk of the carrier charging you air-time twice, once for (attempting to) deliver the call to your phone and than again as an outgoing call from your phone to the voicemail number. Which can be horribly expensive when roaming internationally. Unconditional call forward prevents that as no attempt is ever made by the carrier to deliver the call to your phone.