Cell Phone in London and area

The easiest (but perhaps not the cheapest) solution will be to buy a phone & SIM from one of the "travel phone" firms such as iRoam, Cellular Abroad, Telestial or Mobal (there are others). Many of these use SIM's with UK-based numbers and operate on a PAYG basis, and some have phones as low as $29. The advantage of this system is that you'd have a working phone as soon as you step off the plane.

You could also wait until you get to London and then just stop at the nearest Carphone Warehouse or other mobile shop, and buy an inexpensive PAYG phone there. The advantage of Carphone Warehouse is that they sell products from a variety of cell networks, and can therefore provide the best phone and calling plan to fit your needs.

OTOH, if you go to a shop operated by O2, EE, Vodaphone, 3 or one of the other networks, you'll only be able to use the phones and plans that they offer. One other point to mention is that there are a huge number of MVNO phone operators in the UK. They don't actually own or operate networks, but purchase time with the firms that do operate the networks and then re-sell it. A few examples of MVNO operators are Virgin, Tesco Mobile and TruPhone. Whether you want to use one of these instead of the actual cell network operators is a matter of choice.

Yes, but for a phone to work it needs a SIM card. The SIM card is sold by the phone service provider, it is your link to the phone network, the SIM card decides what your phone number is and which provider bills you. You can switch a SIM card from one unlocked phone to another at any time.

You should be able to buy an unlocked phone from about £20 in the UK. For example
here: http://www.tesco.com/direct/sim-free-nokia-130-mobile-phone-black/257-4493.prd?skuId=257-4493
I assume the price wherever you are will be similar.

But, if you buy a SIM card in the USA, it will be from a US provider, it will have a US phone number and you will have to ask the phone provider how much they charge to make and receive calls in the UK.
If you buy a SIM card when you get to London, it will be form a UK provider and it will have a UK phone number. This will be cheaper for making calls to and from the UK (or other countries in Europe), but, you will not know the number until you gret to London and buy the card.

If you need to give people your new number before you leave, you need to get a SIM card from a US provider that gives you a good deal for "roaming" in the UK.

What is more important to you? Having a US based number that works in the England or cheaper rates? For example: My wife didn't want to mess with an overseas SIM card. She has Verizon. They have a couple(?) of different plans. She paid $25 in 2014 to use 100mb of data and text and talk with her phone. At the end of our 10 day trip she ended up paying $50 because she went through her 100mb of data and then some which caused us to be charged an additional $25. I on the other hand, used an unlocked iPhone 4s. I bought an O2 sim card at a corner shop for 10 pounds. That 10 pounds gave me 500mb of data, talk and text. I did not use all of it while traveling through England and Scotland.
If the "vendors & others" are England based then a local SIM would be best.

It would help to know your phone company? I have Verizon and it's very easy to buy a plan that gives me talk, text, and data overseas. Most companies offer something similar...

As you can see, the "best" answer depends on your particulars. Are you going to be making a few calls or a lot of calls? Or will you be mostly (or only) receiving calls? Will texts work instead of calls? Do you need data as well? What is your current phone model and your current US carrier? Does it matter if your phone number is a US one or a UK one?

Yes, it's a lot to answer, but only with this information can people give you the best help. You're confused because it can indeed be confusing - and only with more specifics can people guide you.

If you have to have "vendors and others" contact you while you are in London, why not just keep your existing phone and either get the European plan your current phone company offers or just do nothing and pay whatever roaming charges are? Don't do texting or any data using activities because that is where the major expense is, except when you are connected to WiFi. Definitely the easiest option and your phone (iPhone or Samsung especially, unless it is an antique) should work perfectly fine.

I did nothing but use my phone last time I was in Europe and spent a total of $10 (for a 5 minute call back home) over what my normal monthly charges were.

Chris F.,

"But, if you buy a SIM card in the USA, it will be from a US provider, it will have a US phone number and you will have to ask the phone provider how much they charge to make and receive calls in the UK."

That's not always true. I used a "travel SIM" purchased here for several years, and it was issued by O2 and had a U.K. number. The rates were set by the MVNO, and were consistent for use across most countries in Europe. It's difficult to say whether rates were much different to those of U.K. customers, as this depends to a certain extent on which calling plan each person chooses. They also provided the option of a local number in my area, which was mapped to the travel SIM. Anyone calling that local number would reach me where ever I was.

The travel phone firm that I used in the past, now provides a SIM which is usable not only in Europe, but also North America. I haven't checked their current prices as I'll be roaming with my home network on my next trip.

Double check with your cell provider here.

I took my (Sprint) Galaxy S4 to London in May. I called Sprint, they asked a couple questions and walked me through a couple settings changes, and I had unlimited texting and unlimited data for free. (Voice was $0.20/minute but what barbarian talks on the phone anymore?)