Setting up voicemail on your iPhone can be a confusing business. There's no voicemail app on your iPhone that provides quick access to the main voicemail options, so you'll need to check with your individual mobile network provider to see what voicemail options are available and how much they cost. However, there are a number of key features that you need to know about when using voicemail.

iPhone Voicemail: VoiceMail Value

Whenever you sign up to a new mobile network or switch to a new tariff, you should ask if voicemail is included in the tariff. Some tariffs include voicemail as part of your monthly contract, but many will charge you extra for using voicemail. Those extra costs can really mount up so it’s important to find out how much voicemail costs on your tariff.

Some networks charge a flat monthly fee to use voicemail, while others charge for each individual voicemail message, or charge by the minute while you're connected to the voicemail system. Some networks even charge you for simply recording a voicemail message - even if you never bother listening to the message.

We’ve heard frightening stories of people who have been hit by huge bills because of annoying marketing calls that went to voicemail, so that's something you really need to avoid, such as this article in the Telegraph.

iPhone Voicemail: Turn It On

Even if your tariff includes free voicemail the chances are that it’s not turned on by default. Turning voicemail on or off is generally quite straightforward, as you just need to dial a special number on your phone. With Vodafone you dial 1211 to turn on your voicemail, or 1210 to turn it off, and most other networks work in a similar fashion.

You’ll also have the ability to add a PIN to your voicemail service for extra security. This is one thing that you can do right on your iPhone – just go into your iPhone’s Settings panel, and scroll down to find the settings for your Phone app.

Read next: How to block callers using unknown or hidden numbers

iPhone Voicemail: Hack Attack

Some mobile networks automatically set up a default PIN for your voicemail system, which may be something as simple as ‘1234’. That’s really easy to guess, so if someone knows your mobile phone number then they may be able to get into your voicemail just by guessing your PIN.

Many people don’t even know about this PIN option, so they never get around to changing it to something a bit more secure. That’s how the whole News Of The World hacking scandal came about, so you should always remember to create a new PIN for your voicemail that will be harder to guess. And if you’re even remotely famous it’s probably worth changing it every few months as well.

The reason these hacks work is that it is possible to access your voicemail from another phone by calling the voicemail number for your network and then entering your unique  voicemail PIN. For example, If you are with EE you can dial 07953 222222 from any phone and just enter your voicemail PIN to listen to your messages.

Read next: Complete guide: How to update iOS on iPhone or iPad

iPhone Voicemail: Remote Access

Most mobile networks allow you to contact your voicemail system from another phone. This can be handy if your battery is flat, or if you don’t want to rack up extra costs when you’re overseas.

Some networks will provide a special number for you to ring, although with O2 and some others you just have to dial your own mobile phone number and then hit the * key to enter the voicemail system. Again, you’ll need to make sure that you’ve set up a secure PIN for your voicemail to make sure that none of Rupert Murdoch’s minions can hack into your voicemail from the comfort of their desk.

iPhone Voicemail: How many rings before answerphone

Many people complain that they sometimes miss calls on their iPhone because it only rings three times before diverting the call to your voicemail system. The length of time that your iPhone will ring before activating voicemail is actually controlled by your mobile network.

My iPhone rings for 15 seconds – which is actually eight rings – before it goes to voicemail, but even that’s not long enough if I’ve put the phone down in another room or it’s zipped into a pocket in my jacket.

However, most networks do allow you to adjust the length of time that the phone rings before switching to voicemail by dialing in a long code number. On Vodafone this is **61*121*11* followed by the number of seconds and then the hash symbol (#). So to set your phone to ring for 20 seconds you’d dial **61*121*11*20*.

Read more about stopping your answerphone kicking in too quickly here: How to stop my iPhone going to voicemail after three rings

iPhone Voicemail: Visual Voicemail

Apple was one of the first companies to include Visual Voicemail on its phones, starting way back in 2007. Rather than having to dial into your normal voicemail system and listening to recorded messages in a fixed sequence, Visual Voicemail shows you a list of your voicemail calls on your screen and lets you listen to them in any order simply by tapping the call in the list.

You can also delete messages without having to dial into the normal voicemail system. Unfortunately, UK networks have been slow to adopt Visual Voicemail, and it currently just seems to be O2, EE and Orange that offer it to iPhone users. It’s not available from major networks such as 3 and T-Mobile (even though T-Mobile is now owned by EE).

In fact, Virgin’s customer service didn’t even know what it was when we contacted them. And if your network does support Visual Voicemail you’ll still need to check with them to see if they charge any extra for it.

iPhone Voicemail: Storing And Deleting

It drives me mad when I get put through to someone’s voicemail system – only to hear a message telling me that the voicemail-box is full, so I should just bugger off and leave them alone. The number of messages that your voicemail system can store will vary from network to network – Virgin provides a free voicemail option that stores just 10 messages at a time, but you have to pay extra for its VoiceMail Plus service, which stores up to 30 messages.

The length of the message counts too, so BT Mobile lets you store a maximum of 150 minutes at a time, with individual voicemails capped at seven minutes each. Some networks also limit individual voicemails to just two minutes.

You can delete individual voicemails as you listen to them, and most networks will automatically delete old voicemails after 30 days. However, few networks offer a simple way of deleting multiple voicemail messages when your mailbox is full – unless you can use an option such as Visual Voicemail, which lets you delete messages with a quick tap of your finger.

Read more iPhone tutorials:

How to get someone else's Apple ID off your iPhone

How to tell if someone has blocked your phone number on their iPhone

How to download YouTube videos to iPad and iPhone

How to speed up iPhone

How to unlock an iPhone so you can use any SIM