Author Archives: David North

Call forwarding for the walking club

My walking club makes use of some clever technology which at least one other group has asked us about, so I thought I’d write it up here…

We list all our upcoming walks on our website, and there’s usually one every week. We like to publish a mobile phone number for the walk leader so people can check the rendezvous and ask any questions. However, leaders are sometimes less than thrilled at the idea of having their mobile number on the internet. Our website had all sorts of hacks built into it – displaying the numbers as images and removing them after the event had passed – which were holding up our move to a more off-the-shelf CMS.

That’s where I came in. The idea was to publish a single phone number for all walk leaders which forwards to the right person for the given week – no more privacy concerns and everybody happy.

This is not new; it’s the sort of thing VOIP providers have been able to sell you for years on a “normal” geographic phone number like 01865 xxxxxx. However, publishing that on the website would cause all sorts of confusion; people most often call on the morning of the walk when we’re already out on the ground, and would be put off calling a “landline” number because they’d think it was a home number.

This is where one of my favourite tech companies comes into its own: Andrew and Arnold now sell normal 07xxx mobile numbers on VOIP.

For the calls, it’s dead simple – just use a web page to specify the “target” number (or numbers plural if you’re feeling adventurous):

This works completely seamlessly and even passes through the original caller’s caller ID to the target phone. It costs £1.20 per month for the number plus a per-minute cost for forwarded calls, which is currently 3p per minute for UK mobiles. That makes it very cost-effective for a cash-strapped walking club – the whole thing costs us less than £30 per year.

We also make use of the “time profiles” feature to limit calls to 8am through 8pm after an incident where someone called unreasonably late.

Texts are a bit messier (although in practice we find people rarely use them). But it’s an 07 number and people expect to be able to SMS it, so we made it work. Unfortunately you can’t seamlessly forward texts (because AAISP don’t want to allow “forgery” of texts “from” the original sender, which I can understand). One option is to e-mail them somewhere, but the method we use is to have them sent to an HTTPS page which I host, which in turn uses IntelliSMS to send a text a bit like this:

Clicking the sender number on most phones allows the reply text to be started pretty easily.

Golf Mk5 side repeater replacement

LED side repeaters built in to the wing mirrors may look cool and be more aerodynamic, but after 11 years and 101,000 miles, the one on the left of my Golf GTi failed. And unlike any other light on the vehicle, you don’t just buy a bulb from Halford’s for £2.99 and swap it over in five minutes…

These instructions, although eight years old, worked nicely. Having the new part in my hand (GSF Car Parts, twenty quid plus delivery … annoyingly, this is something EuroCarParts up the road from me don’t stock) I could see that it included two of the trickiest plastic tabs, so I snapped the old ones off with my screwdriver rather than trying to un-tab them.

It cost me 45 minutes of my life, but to save the £75 or more a main dealer would have charged, worth every penny.

 

3 SIM meets the OnePlus Two

Out (and back in) with the old, in with the new.

Three’s new pay monthly SIM took quite some bedding in to the OnePlus Two. It needed nearly 24 hours, multiple reboots of the phone, and finally booting the phone with just one SIM in it before all sprang into life and started working.

Having been through all that, this is where having a dual-SIM phone comes into its own, because I can start using data via Three right away and keep taking calls via EE until my number port goes through.

ApacheCon North America 2017

I’ve spent the past week out in Miami for ApacheCon, and thought I’d share a few things.

Getting there

We flew direct out of Heathrow on BA. Eight hours in cattle class world traveller is never going to be a fun experience, but BA do lay on a decent quality and quantity of food and drink even in the back. Getting through US Customs was a bit of a pain, but even though the automatic system diverted us for extra review, it didn’t take very long (obviously we’d applied for our ESTAs and had them approved before going).

America

It’s worth reading up on US tipping culture before going (and noting that you need to write the amount on the bill when they bring it if you’re tipping by card). I’d not been to the states before, but with that knowledge pre-consumed, it was all pretty much as expected. The Americans are a lot more patriotic than us, and have their flag all over the place, including at the airport and some impressively huge ones hanging off buildings. On average, I found the customer service and general standard of friendliness higher than in the UK.

120v

American sockets put out 120 volts, not the 240 we’re used to in Europe. Every device I took with me was labelled as coping with either, and did, but it’s worth checking the label before you plug it into an adapter.

Money

It’s worth looking up the sales taxes for the state(s) you’re visiting – be aware that, often, none of the prices you see quoted will include them.

Chip and pin is present in some places, but a lot of retailers are still using the old magnetic stripe, meaning they can wander off with your card and come back with the receipt for your payment (Monzo works everywhere as you’d expect, and it’s handy to have a card you can load just-in-time and see instant notifications for when the security is rather slacker than in the UK).

Uber (yes, I know, contentious stuff) Just Works if you’ve got an account created in the UK (and if the city you’re visiting is covered, of course). They may have a sketchy reputation in some quarters, but it’s damn useful being able to set up your work card and charge taxis directly to it without having to faff getting a receipt from the driver and claiming it as out of pocket expenses. Indeed, armed with this capability, cash was barely necessary for the whole six day trip.

The event

I’ve been to ApacheCon in Europe twice before, but not to the US. I got the impression there were a few more people and tracks of talks than we had in Seville last autumn. The standard of the speakers was generally very high (I hope I didn’t lower the average too much) and there were an interesting bunch of vendors giving out swag and potentially useful information about their products and services. We also did some good networking and had lunch every day with what one of my colleagues aptly titled “POIzone”, a bunch of Apache POI and Tika commiters, several of whom I met in person for the first time.

My talks

I did three talks, one on Containers: Not Just For the Cloud? (Slides, video), one on Apache POI and the challenges of working with a 16 year old Java codebase (slides) and a lightning talk on a recent side project (video – starts at 2:41).

All in all, a fun and educational week, but some jet lag to overcome before getting back to reality on Monday.

Voice calls need to grow up fast

So I’m out in Florida for ApacheCon, and it’s been a really fun and useful trip so far. But it got off to a shaky start. After over 8 hours in a tin box flying from London, we get to the hotel in Miami, check in – mercifully brief – and do our best to stay awake until 10pm local time before crashing out. We arrived a couple of days before the conference proper, so plenty of time to adjust.

Picture the scene: 4.30AM local time, the rasping sound of someone sawing wood as I adjust to Florida time.

> Bzzzzzzzzzzz < > Bzzzzzzzzzzzzzzzzz <

Hello?

Hello, sir. Are you aware your credit card was used in America?

Would that be the same “America” that I filled in the “notify overseas travel” form on your website for a week ago?

At the end of this three minute conversation, I was £3 poorer. Thanks EE.

The truly tragic thing about this exchange (apart from HSBC’s inability to interface with their own systems) is that, back when I was at school (over 10 years ago), I remember reading a piece in PC Pro by Jon Honeyball about this exact situation. He talked about wanting a phone system smart enough to look up his diary in Outlook and tell the caller “it’s 4.30 AM local time where David is, press 1 to wake him up if it’s desperately urgent, but beware of his reaction”. Ten. Years. Ago.

What’s even worse is that this almost exists. Andrews and Arnold have some really cool products including the ability to port your 07 UK mobile number to their VOIP service, which includes the fabled time zone announce feature. OK, so it doesn’t integrate with my calendar, but I’d be quite happy to script that or just set it manually for trips like this one.

So why haven’t I ported my mobile number to their service? It would allow me to use SIP to pick up and make calls over the internet when abroad (this works surprisingly well using WhatsApp, so the bandwidth does exist), cutting out horrendous roaming charges, as well as having the time zone announce and other features.

Unfortunately, there is one crucial piece of the puzzle missing which makes me reluctant to go VOIP+Sip2Sim for my mobile: by default, SIP sends passwords in plain text (updated after twitter conversation with RevK) using a challenge-response and a digest, which feels more vulnerable than simply using TLS on the signalling. This is just about bearable on a fixed-line home or work internet link, but feels risky on a semi-public WiFi network like the conference one here (especially considering the potential financial consequences of a leaked set of VoIP credentials).

AAISP, please fix it so I can drag my mobile number into the 21st century.

Door sensors: Energenie vs Hive

I’ve had a Hive door sensor for a while now, as regular readers will recall. Recently I wanted an similar device for a side project at work. In that case, there’s no pre-existing Hive infrastructure, so the Hive option didn’t make financial sense.

Energenie do a nice door sensor for £20, but as with all these devices, it speaks to a hub which needs buying separately. I managed to find one of theirs online for £40, which is a bit much for such a simple thing, but the cheapest option out there.

The Energenie app isn’t as nice as Hive (the notifications say “a sensor has been opened” but you have to tap to see which one, which is a bit silly). It does however talk to IFTTT perfectly.

I suspect it can also be made to talk via their Raspberry Pi connector, but I haven’t had a chance to try that yet – and I must admit IFTTT + web hook was really easy to get working without writing much code.

VPN

The world has moved on a lot since I last tried to set up a VPN endpoint for my Android phones to use. The Debian instructions on OpenVPN mostly work out of the box, and clients are available for all OSes, mobile and desktop.

screenshot_20170506-201230

Virgin Media

We got a Virgin Media (business) line in the church office recently, and although it was quite unstable for the first few weeks, it has now settled down nicely. I can run my monitoring on the end of it without getting lots of false alarms:

vmedia

Colour me impressed, especially for what we’re paying.

Cycle camera

I’ve started cycling to work regularly again, and got myself a helmet camera. This is one of those annoying areas where there are cheap items made in the far east, or very expensive items made by more recognised brands. There doesn’t seem to be anything in between.

So, I took a punt at the cheaper end, and here it is:

img_20170422_095710

As you can see, the only part of their fixing accessories I used were two velcro straps; the camera feels most stable and doesn’t un-balance me when it’s strapped tightly to the middle of my helmet.

So, what do the videos look like? Here’s a thrilling clip of my commute yesterday morning:

I had no idea I moved my head so much when cycling, but it’s not bad quality – certainly good enough to get a number plate in the unpleasant event of someone cutting me up or knocking me off. I might try it on the handlebars next.

Needless to say, the camera does not claim to have any night vision at this price, but on lit streets, it’s possible to make out registration numbers of most overtaking cars if you step through the footage frame by frame.

Configuring it involves a txt file which it writes to the SD card, but once you’ve set the date and time, there’s not much else to worry about. The battery doesn’t last very long, but it only takes a couple of hours to charge over USB, so not bad. The inbuilt microphone just picks up wind noise when any sort of motion is involved.

Obviously, the £40 cost of the camera is then bolstered by buying the biggest micro SD card you can afford. At 90MB per minute of footage, it soon fills up. The way it records in chunks (maximum 10 minutes each) is a bit silly, but there are plenty of tools on Linux to concatenate the chunks together again.