[Closed] Best (cheapest) PAYG with voicemail

I need a PAYG with voicemail for as cheap as possible.

It's for a sports club, to have a results service so coaches / team managers can call or text results from games so I can then collate them onto a results email and onto the club's website. I don't want to use my home phone or own mobile, because i want the convenience of it being on voicemails (and i'd probably answer my own phone, then have to find a pen to write the message down, etc.); plus if I'm away anywhere someone else can have the phone.

I've got an old S5830 Samsung Galaxy Ace so don't even need the phone, just a SIM.

Have been looking on line but I'm a numpty at this, and it seems a lot of PAYG options have an expiry (eg: you buy a tenner of credit, but it only lasts a month whether you use it or not. How is that PAYG, looks like a monthly rolling contract to me?)