Cell phones

I get an ATT Passport plan when I travel and the options vary between the 3, but the Silver had texting included to US, and a certain charge per minute for intl calls, and I usually make a few local calls to taxi companies in the country where I'm staying and don't recall there being a costly charge for that. Unless you need a huge amount of data for some reason can you just use free Wi-Fi?

Just head to a Carphone Warehouse once in London and tell them what you need, in about 10 minutes you will walk out with coverage.

I was there in June and they had a special, something like 3 gigs of data, local calling and texts, prepaid, for 10 pounds, normally 20 lbs. If you also want to text or call overseas (or just to your US phone you have with you) I suggest having them top it up with 5-10 lbs for you, since that will cost extra and you will need a balance to draw from.

For the SIM I got, O2 was the carrier, but if just in London, I do not think the actual carrier matters.

blimey - with all those lbs that's a might heavy SIM

Three (3) has a 30 day PAYG SIM for £20. It comes with 12gigs of data and local calling/texting. I have a Skype account and used that for calling internationally. My hotel had horrible wifi so the huge data plan was great.

You have to go to a Three shop, it's not available at Carphone Warehouse.

We used Orange and O2 previously, now we just use the AT&T passport and limit use.

Just got back from two weeks in the U.K. and for the second time we purchased SIMs from EE (Everything Everywhere). Great service and coverage. We got 4GB plans for GBP 25 which turned out to be double what we needed as I used just shy of 2GB despite what I felt was heavy usage.

Thank everyone for the excellent info. I think i will stay with my original plan. I will put passport on our phones and bring my old unlocked iphone 5S and buy a sim card once i get there. that should cover me for whatever arises. I do have one other question on the silver passport plan I was reading that i could send text back to the states, but only if i use SMS texting. Can anyone explain what SMS texting is and how do i make sure that is what i am using on a iphone 6Plus

An interesting note: We took our Verizon phones with their extra service.
We came upon a woman who had fallen and had a pretty impressive gash on her knee. I dialled 999, the emergency number and nothing happened. I tried several times and then, on a hunch, I tried 911. It connected me to the 999 service. This was in London. Not sure if that's how it is supposed to work,

You said "but only if i use SMS texting. Can anyone explain what SMS texting is and how do i make sure that is what i am using on a iphone 6Plus"

SMS is the "open standard" (short message service) texting protocol used by cellular networks. When you SMS text someone on your iPhone, the messages you send are colored green.

The other protocol used by iPhones is the Apple-proprietary iMessage protocol. When you text someone who is also using an iPhone, that message is colored blue. In days gone by, iMessages didn't count against your "Text" cap but that is just about academic because all (American) carriers now include unlimited texts.

You might also need to change the phone numbers in you address book to include the USA country code in order for texts and calls to go out.

911 should connect to the emergency services from a mobile phone operating on a UK network, but this is unpromoted. 112 / 999 are advertised. 112 is part of the GSM standard.

911 will not connect to the emergency services from a landline as a local number can start with 911.