With coverage in developed nations as good as it is now, and mobiles as prevalent as they are, the backup USIM case is very niche.

I'd go so far as to say that encouraging people to have a separate handset just for the case of when they forget their main one AND need to make a call that can't wait AND don't have anyone else around to borrow a phone off AND are not within walking distance of a payphone is not only irrelevant but also environmentally irresponsible. Maybe that's why MNO's don't encourage or facilitate it.

/m

I doubt the operators would embrace such forward thinking though, most of the UK ones don't even bother acknowledging certain GSM divert codes!

Swapping SIMs – why would you want to do that? I would see cars having their own SIMs (with unique IMSI) onto which the MSISDN (phone number(s)) of the passengers could be mapped. Look on it as something akin to Bluetooth pairing – when you get in the car you incoming phone calls ring the in-car phone (in parallel with your personal handset).

Is this possible/feasible? Why yes (particularly if one is a Research Director for a mobile operator with GSM infrastructure – which I am!)

Most of this functionality is already here – In the US the OnStar system is pretty popular, with 5m subs across the US & Canada. It's CDMA on Verizon, and you can pay extra to use it as voice, not just emergency help. Not sure about the rates tho, their site is down.

The need to swap USIM's is a barrier to this sort of thing, and I can't think of an MNO offering a dual-SIM auto-divert anymore. Much easier to use autoforward on no answer IMHO, esp. with Spinvox to glue the end-message delivery together.

When Onstar recently changed from Analogue to digital, just the replacement CDMA module was $200.

/m

There are so many advantages that this could offer, including:

– Increased peformance – external antenna plus built in handsfree
– Location tracking of the car, linked to a myriad of LBS applications
– Remote assistance – summoning help if you crash, unlocking car if you lose your keys, disbling engine if stolen
– Pairing with personal handset – when in car, calls to personal phone 'parallel ring' car phone
– Providing data bearer over which automotive systems report and are remotely updated
– Every car becomes capable of 'mobile mapping' – building up coverage/location maps
– Mobile WiFi access points – think JoikuSpot in every car, providing passengers with WiFi based internet services

And I think that we could go on further!

2008/10/7 Disqus <>

there are 3 fundamental reasons to not have a handset with you, in any situation:
1. inconvenient
2. not allowed/feasible
3. no compelling reason to have the handset

take the converse of these and show WHY anyone might have a handset on their person:
1. convenient
2. required (i.e. my job function requires that i have a blackberry, etc)
3. a compelling reason exists to have the handset on my person

—

now consider where you fell short: you had no reason compelling enough for you to inconvenience yourself with a handset you didn't really need on that short trip. fix ANY of those problems, and you'd likely have had the handset with you. take these possibilities:

1. inconvenience: this is how you're suggesting to fix the problem. make the handset extremely convenient by always having it in the car. can't get anymore convenient than that. of course, long term, you've got some issues like cost, maintenance, etc. and this only helps you in YOUR car and only when you don't have ANOTHER handset on your person…

2. allowed/required: this doesn't apply to your current situation, but it's important in other situations to make this general algorithm require at least a mention of it. here, the handset is neither required nor forbidden: it's your choice alone.

3. compelling reasons: “in case of emergency” might be a compelling reason for some people, but almost never suffices for those who have had mobiles for more than a year or so — unless they feel unsafe on a regular basis. what about the camera on the phone? mobile email? weather alerts? the ability to check prices online? play a game when you're bored? these are all well and good, but require action from the user — there is no intrinsic value to always keeping the phone on you. but rhere are other cases where there IS intrinsic value to keeping the phone on you at all times:

1. LBS: location based services, like perhaps having a TODO list that triggers when you've moved nearby the location requiring you to perform an action.

2. how about good-ole Nokia Activity Monitor (Step Counter, etc)? i keep this running all the time. not so much because i'm trying to be healthy, but so i can figure out when i was where: i KNOW i was at work by 8:30 because the step-counter flatlines at 8:30 am. an lunch? why yes, i took a LONG lunch break, i can see that in my step counter's records. so, rather than try to work out my time sheet as i go, i can rely on this information to give me starting and stopping times later on… maybe there are much better purposes for this info – regardless, if step counter is always running you've got a history of this info available for future reference.

—-
this is where i think you're going the wrong direction: don't look for ways to make having a handset more convenient (unless you've got a monster of a device, i've never carried an E90 so i can't say whether i'd be willing to). a better option is to find ways to make carrying the device more compelling – otherwise even the most convenient device out there will eventually be provide some degree of effort and become the next device you don't have on your person when you need it.

-bit

The car mobiles are also a different network from my (and wifes) network – so that if we hit a dead spot – there is a chance the second phone will work.

Just make sure you always have your own mobile on you when you go out. Or that you’re with someone who has one with them instead.