I've just spent more than a week trying to find out of the millions of
plans offered by UK operators one that would offer decent data charges and
roaming charges in the Republic of Ireland. Trying to find a clear rundown
of the charges, bundles and restrictions on the various operator's web
sites turned out to be a complete nightmare with charges for the various
services scattered all other the place and often either missing or
misleading. So in case anybody else is looking for a proper data plan or
spend their time between Northern Ireland and the Republic, here is what
I've found out:

- O2 is the best for roaming in Ireland. With O2 PAYG and their £2/month
option (forgot the name but you'll find it hidden away somewhere on their
web site), you get free roaming in Ireland for calls and texts. I suppose
that this option also exists for O2 Contracts. O2 coverage is very good in
both the UK and the Republic.
Only problem: data on O2 PAYG seems to be limited to wap and O2 emails. You
don't get full Internet access. Data charges are dear anyway at £3/MB in
the UK and something stupid (£8/MB IIRC) when roaming. You do get full
internet access on contract apparently but their data bundles are
ridiculously expensive.

- Next in line is a Three contract. With their Three Like Home offer, you
get to roam for free on Three networks in selected countries which includes
the Republic of Ireland. Free roaming includes data.
For data, they offer their X-Series option which is presented in an uterly
confusing way (in some places they talk about unlimited web browsing while
in other they state unlimited internet access which are 2 completely
different things, their X-Series page seems to imply that you can only use
the listed applications to connect to the Internet) but according to
numerous posts from people here and on other forums it seems to give you
full unlimited (unlimited according the mobile operators definition of
course which means limited in many ways) Internet access for an extra
£5/month on top of your contract (that's the X-Series Silver plan).
The only problem with Three is that the only thing that's really unlimited
with them is their list of restrictions and limitations:
* Three Like Home gives you free roaming only if you are roaming on the
Three 3G network. In Ireland, there 3G coverage is pretty bad which means
that if you're outside big towns you'll be roaming on some other network
and have to pay Three's ridiculous roaming charges.
* Data connections are only available where you have 3G coverage. If you
are in an area without 3G coverage (be it in the UK or abroad), you won't
be able to use data *at* *all* no matter how much you're willing to pay for
* X-Series T&C prevent you from using your phone as a modem for your laptop
and there is no extra option you can buy to get that. Gerry here has
mentionned that using your X-Series phone as a modem works but you can't
really rely on it.
* Three contract phones seems to be crippled in that you can't set them to
use 2G only. This means that if you're an area with poor 3G reception
(which is might happen a lot in Northern Ireland and the Republic outside
big towns) you won't be able to switch to 2G only to get better reception
or simply save battery life
* Three contract phones are locked to Three and you have to wait until the
end of your contract to be able to get an unlocked code (unless you're
willing to pay stupid money).
* Apparently, Three gets angry when you try to use a Three SIM in a
non-three branded handset which means that if your Three handset breaks
down, you're in trouble as you might not even be able to use an old spare
phone you have without getting hassled by Three.

- Last in line is a T-Mobile Contract with their Web&Walk data plans.
T-Mobile 2G coverage is pretty good in the UK and in the Republic (they use
Meteor there). 3G coverage in Northern Ireland seems to be limited to the
Belfast area (hard to say for sure since I couldn't even find a UK coverage
map on their web site, only a bloody useless coverage checker which only
shows you coverage in your street). Roaming charges even in the Republic
are ridiculous for both calls and data. With their WorldClass option,
you'll be able to make calls for 25p/min in the Republic but receiving a
call will cost you 50p/min (that all comes on top of your monthly line
rental of course). Roaming data is £7.50/MB. Their Web&Walk plan will give
you unlimited (again unlimited but limited) internet access in the UK for
an extra £7.50/month on top of your monthly line rental (no modem use) or
£12.50/month (modem use allowed).

T-Mobile PAYG might also be an option. Roaming charges on PAYG are even
worse than on contract (data is still £7.50/MB though). On PAYG, data is
charged at £7.50/MB even when you're in the UK but while you stay in the
UK, data charges are capped at £1/day. So for occasional heavy data usage,
this might be quite good. Modem use not allowed though as far as I know
although it should be working anyway.

So that's about it unfortunately. I considered getting a Three contract
with a free Nokia N73 and keeping an O2 PAYG phone for the places in
Ireland with no Three coverage but the only N73 Three offered were
refurbished and only available on 18 months contracts. It would have cost
me over £600 over 18 months on their cheapest contract. Given all the
limitation with Three, the fact that the phone was not even new and that I
didn't really feel like being tied to an far less than perfect 18 months
contract, I decided to get the phone SIM-free (£250 at expansys.com), get a
T-Mobile PAYG SIM and keep an O2 PAYG for the Republic. That leaves me with
£20/month to spend on top-ups so it might ultimately turn out to be even
cheaper than a contract and at least I'm not tied to anything, I can switch
to another operator antyime I want if one comes up with a better tariff and
I get a brand new phone with no branding, no crippled firmware and

Good luck to anybody looking to get a proper contract in the UK and is more
interested in data and roaming than having dozens of thousands of minutes
and texts. It's a bloody nightmare.

See More: Proper data and roaming in Ireland plans - the rundown