Caller display setting up and question about Voicemail

[#1]

I see I can set up caller display at 99p/month. Once I tick the box, does that commit me or can I stop it at any time.
Regarding Voicemail, which appears to be free, is this anything like BT 1571 (which I never used to use when with BT). How does a user know if there are messages waiting?
Thanks

[#2]

After ticking the box(es) you need to click the "add features" button in the Order Summary box on the right to place the order. Once activated I think you need to pass a billing date before you can turn features off. Turning off is done using the Remove call features tab which is next to the Add call features one you are shown by default.
The free Voicemail feature is the same as BT 1571. When messages are waiting the dial tone becomes a stuttering one when you pick the phone up. But that's the only message waiting alert. If your phone has an answer machine I think many users find leaving Voicemail off is best (I do even though it's free). However Voicemail Extra which costs £3.00 per month and offers additional features might be worth a look.

[#3]

Thanks. I might need to switch on Voicemail (the free one) as our BT4500 phone is unreliable with the Answerphone on at capturing messages. I don't know if it is being affected by the (Plusnet) router or not. I have it about 4 feet away from it.

[#4]

The free voicemail service will answer after 7 rings if you have it. To ensure your answer machine picks up calls that needs setting to answer on fewer rings. By default my BT6500 answers on 5 rings since 1 ring's worth of time is taken up whilst its call blocker function classifies the call.
I've heard of DECT phone base stations affecting ADSL routers, haven't heard of the reverse. It possibly depends on the proximity of cable runs as well as base station and router.