Is it best to buy an iPhone 4 now, or wait until the iPhone 5 launches? PC Advisor investigates.

The Apple iPhone is one of the most popular smartphones in the world to date. If you haven't already got your hands on the iconic device, then we guarantee that you're either currently considering opening your wallet ready to hand over your hard earned cash in return for the shiny device, or you have done so in the past.

One of the questions I get asked most by friends, family and our readers is 'should I buy an iPhone 4 now or wait until the iPhone 5 comes out?'

See also Apple iPhone 5 launch: as it happens

iPhone 4 or iPhone 5?

It's worth pointing out that Apple has still not confirmed it is planning to release a new version of the iPhone. However, speculation is mounting on the web (check out our iPhone 5 rumour round-up for all you need to know) and with the recent loss of an Apple smartphone prototype in a bar in San Francisco, we can make an educated guess that it's coming, and hopefully sometime soon.

Another indicator that the iPhone 5 is on its way is the reduction of pay monthly iPhone tariffs from mobile networks. Compared to the time of the iPhone 4 launch, when Orange was offering the iPhone 4 for free on a £75 per month contract that came with unlimited calls and texts, the operator now has a deal available that will give Brits a free iPhone 4 along with 1,200 minutes of calls and unlimited texts and data for £45 per month.

Likewise, Vodafone was offering the 16GB Apple iPhone 4 for free on a two-year £60 per month contract with 3,000 minutes, unlimited texts, 1GB of data, 1GB of Wi-Fi access and 5MB of European data roaming per day. Now, the network is offering it for free on a £41 per month tariff with 900 minutes, unlimited texts and 750MB of data.

Similarly, at launch, O2 and T-Mobile were also both offering the 16GB iPhone 4 for free to Brits that opted for a £60 per month, two-year contract, but it's now available at no cost on a £42 per month contract and £40.85 tariff respectively.

The fifth of the UK's major mobile networks, 3 has also followed suit and reduced its iPhone tariff price. Originally, 3 customers could get their hands on a free 16GB iPhone 4 on the £45-per-month contract that included 2,000 minutes of calls of landlines and other mobile networks, 5,000 minutes of calls to other mobile users on the 3 network, 5,000 texts and a data allowance of 1GB. However, the price has now dropped by £5.

These are all certainly value for money deals, so should you take the plunge or hang on for the new handset?

NEXT PAGE: How the specifications of the iPhone 4 and iPhone 5 will differ

One of the questions I get asked most by friends, family and our readers is 'should I buy an iPhone now or wait until the next version comes out? We help you decide.

iPhone 5 specifications

Let's start by looking at the potential differences between the existing iPhone 4 and its successor the iPhone 5. Of course, once again because Apple has yet to confirm the device's existence, we can only base this comparison on rumours and speculation we've heard.

According to a source cited by Japanese website Macotakara the new iPhone will apparently use an ARM Cortex-A9 processor, though the report didn't state whether it would be a dual- or single-core chip (although an alternative rumour, however, points instead to a dual-core A5 chip). At present the iPhone 4 uses an Apple A4 chip.

Some are speculating the design will be largely similar to the iPhone 4, while published an image of what's thought to be a case for the iPhone 5 that it says came from a Chinese manufacturer. The drawing suggests the handset may have a very different look to the current iPhone 4. The computer generated images indicate the iPhone 5 will have a curved back, similar to that seen on the iPhone 3GS, along with a bigger, 4in edge-to-edge display (currently the iPhone 4 has a 3.5in display) that doesn't have a bezel. Meanwhile, Digitimes reckons the screen will be curved, in a style similar to that seen on the Google Nexus S

It's also thought the smartphone's camera will be boosted from 5Mp to 8Mp.

Buy and iPhone 4 or wait for the iPhone 5: Conclusion

It purely boils down to whether value for money or owning the latest piece of technology is your biggest priority. If items like the camera and the processor, which aren't as powerful as we'd like them to be on the current iteration of the device, are more important to you than having tonnes of minutes, texts and data, then you'll be better off waiting for Apple to release the next version of the iPhone.

However, if in these times of economic hardship, value for money is your primary concern (or like me you're a text and talkaholic) then opting for the current iPhone 4 on a tariff with plenty of minutes and texts is your best option as its likely that when the iPhone 5 is made available, it won't be available free on the same tariffs.

However, it's worth noting that while iPhone 4 users won't be able to benefit from the hardware upgrades seen on the iPhone 5, they will be able to upgrade their handsets to iOS5, the next version of the mobile platform, which the forthcoming version of the smartphone is expected to run. Among the new features iOS5 will include are new-look notifications and support for iCloud, Apple's function that allows users to store their music, photos, files and contacts online and then access them from their iPhone.

(Even if the Apple iPhone 5 has 4G connectivity, that won't affect UK users until we have 4G connectivity, and with the Ofcom 4G auction unlikely to happen until the middle of next year, that means we're unlikely to enjoy 4G much before 2013.)

Finally, we've a quick bit of advice for those that want an iPhone 5 but are still in contract when it launches? When the iPhone 4 was launched O2 ran an upgrade offer for a limited period that allowed customers still in contract to get their hands on the new iPhone. Instead of paying off the remaining contract in full, O2 let customers pay a one-off charge based upon a £20 per month fee for each full month left to run on the contract. The mobile network has yet to respond when we asked whether they would be running the offer with the iPhone 5, but if you're prepared to wait and see, it could work in your favour.