[Ovmsdev] USSD Signaling
Kevin Sharpe ZCW
kevin.sharpe at zerocarbonworld.org
Wed Aug 21 03:54:28 HKT 2013
Three has pretty poor network coverage in the UK and would be of limited use to most OVMS users here.
I tried GeoSIM but results were not great and I would need to keep an unlocked phone with me for traveling around Europe. Indeed on my most recent trip I would be swapping the sim several times a day moving in and out of various countries.
Today I use a giffgaff sim which runs on the 02 network. It costs me £5 per month and provides great coverage in the UK and most of Northern Europe. Only time I've ever had problems with giffgaff is in Switzerland (I didn't have an unlocked phone with me)
Anything that reduces the burden of support is a good thing especially if we wish to grow the number of OVMS users significantly.
On 20 Aug 2013, at 17:13, "Dominik Westner" <me at nikwest.de> wrote:
> if you pay £6 a month in the UK it looks like you have the wrong data plan. The trick for low monthly rates is to have no data plan at all and pay per MB. This should be between 10p - 30p in the UK (just glimpsed at the 3 web site). With this you'll never pay more than £2 a month. Even when doing a 4 weeks trip through Europe I highly doubt that this will be more than £6 a month. I NEVER paid more than 2EUR per month for the last 15 months and my cost is 23 cents per MB (1KB min data size).
> Sorry, don't want to get off topic though.
> If we go USSD this also implies some sort of vendor lock in with the M2M provider as he has to do the routing.
> On Aug 20, 2013, at 3:32 PM, Nikki Gordon-Bloomfield <nikki at aminorjourney.com> wrote:
>> I pay WAY over for mine (£6 a month for data only sim) but that's because I want the continued knowledge that my cost is predictable every month. Considering I've heard (though I can't remember where) that Nissan wants £100 a year for Carwings after third year, I'm happy with that...
>> On 20 Aug 2013, at 14:26, Mark Webb-Johnson <mark at webb-johnson.net> wrote:
>>> How much do you guys pay for the SIM prepaid plans in UK (per month) for OVMS?
>>> Regards, Mark.
>>> On 20 Aug, 2013, at 9:18 PM, Kevin Sharpe ZCW <kevin.sharpe at zerocarbonworld.org> wrote:
>>>> We've seen lots of issues with SIM configuration here and almost ever new OVMS user requires help.
>>>> When driving I've even lost connectivity in some European countries because I've been unable to remove the SIM for reconfiguration.
>>>> Anything that simplifies the configuration overhead would be welcome here!
>>>> Kevin Sharpe | Founder & Patron
>>>> Tel: +44 122 566 7544 ext: 800 | Skype: zerocarbonworld
>>>> kevin.sharpe at zerocarbonworld.org | www.zerocarbonworld.org | twitter.com/zerocarbonworld
>>>> Zero Carbon World is a UK Registered Charity #1141347
>>>> From: Mark Webb-Johnson <mark at webb-johnson.net>
>>>> Reply-To: OVMS Developers <ovmsdev at lists.teslaclub.hk>
>>>> Date: Tuesday, 20 August 2013 15:04
>>>> To: OVMS Developers <ovmsdev at lists.teslaclub.hk>
>>>> Subject: [Ovmsdev] USSD Signaling
>>>> I've had a proposal from a M2M provider that is interesting, so thought I'd distribute it here, and get feedback.
>>>> A very low-level protocol in the GSM standard is called USSD. It involves the transmission of a single alpha-numeric message of up to about 120 characters. Our protocol messages would fit perfectly into it. The USSD protocol is routed at a very low level, and is a datagram-syle protocol (it may be discarded by the network if there is no cellular connectivity, kind of like UDP). The protocol is supposedly better able to make it through congested and low-signal areas than even SMS, and certainly much better than GPRS. Message transit times are faster than SMS at around 1 second (of course, depending on cellular coverage).
>>>> The interesting things about the protocol are than (a) it is free (or flat-rate, at least), and (b) it supports roaming. One SIM, flat rate, globally.
>>>> The M2M provider suggests that we buy SIMs from them with unlimited USSD plans. Once activated, the SIMs would work globally on hundreds of partner carriers, and would only support USSD (not SMS or GPRS data). The way it would work for OVMS would be:
>>>> • Every OVMS module would be provided with a USSD SIM already onboard. It would work globally.
>>>> • The owner would go to the www.openvehicles.com website and create a vehicle record as normal, but also enter the serial number of the SIM.
>>>> • When the OVMS module powers on, it would read the serial number from the SIM then send a single USSD message to us to request provisioning (vehicleid, server password, etc).
>>>> • The OVMS server would send back a USSD message to provision the module in the car.
>>>> • From then onwards, USSD messages would be used to encapsulate our current OVMS protocol messages.
>>>> • The USSD messages are bi-directionally gatewayed to the OVMS server via the M2M provider, over the Internet.
>>>> • There would need to be some small changes to the encryption protocol we use.
>>>> • The OVMS firmware could support this as a special operation mode - based on the prefix of the SIM inserted. So, it could work in normal SMS/GPRS mode as well as USSD mode (switched by the SIM in the module).
>>>> Cost wise, this would increase the cost of the module by less than US$10 (price of the SIM). A monthly flat-rate "unlimited" USSD plan would be around US$8-US$10 per month.
>>>> What do people think?
>>>> Regards, Mark
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