Is it time to subscribe to a printer service from HP?

Ever since my dad brought home an...

What’s the best way of buying a phone today?

How did you buy your latest phone?...

MWC: What device highlights did you miss?

So, early last week I predicted that...

The arse with SMS home routing

Image024

Lately quite a few people have been talking to me about sms home routing. Most people from the industry have been, not to put too fine a point on it, seething with annoyance at the prospect.

‘Home routing’ means (thanks to Wikipedia) ‘that the receiving mobile operator assumes responsibility for the delivery of an SMS, rather than the sending mobile operator.’

That might, at first glance, sound sensible. But I’m not so sure.

Right now the sending operator takes responsibility for delivering its own text messages.

That is, if I, using T-Mobile, send a text to Ed at ROKTalk who’s using Vodafone, my message is queued by T-Mobile who, via their interconnect, communicate with Vodafone’s user directory. (OK so I’m massively simplifying things) They explain they’ve got a message waiting for one of Vodafone’s customers. Vodafone’s user directory receive the request and ask T-Mobile to hold on just a moment whilst they hunt around for the handset on their network. If they find the handset Vodafone informs T-Mobile about the delivery parameters, and then T-Mobile delivers the SMS straight to the Vodafone handset. Then T-Mobile gets a delivery receipt again straight from the handset.

Or, if the message can’t be delivered, it’s [held by T-Mobile for future delivery?] until it can be. All is good. Right? I know what I’m paying for. T-Mobile know what they’re charging me for. All is good.

The KEY point is that T-Mobile — the people I’m paying good money to, for the transmission of that text message — are sitting waiting to deliver my message. They take responsibility for it. It’s their problem.

Home routing, on the other hand, works in this way: T-Mobile pass the message to Vodafone. Vodafone say thanks. We move on. T-Mobile don’t have to bother at all with any responsibility. It’s completely Vodafone’s problem to deliver the message. T-Mobile add the transmission costs to my bill and that’s it. Sounds OK, right? But no. The problem I’ve got here is that I’m NOT paying T-Mobile to send messages to Vodafone, I’m paying T-Mobile to send messages to the Vodafone customer — Ed, for example. I want them to take FULL responsibility for the message delivery.

This is the equivalent of paying UPS to send a package to India — where a nice man in a UPS van and uniform comes to pick up the package, chucks it in the back of the van, arrives at the depot and gives it to some guy on a push bike and asks him to ‘sort it out’.

Cue: A guy in a push bike cycling all the way to India with my package.

No. I want UPS to deliver the package end-to-end. In fancy UPS jumbo jets and trucks. Ok, A warped example, I know. I’m just not keen on the concept of the mobile networks doing the fake smile at each other (“Sure, that message, sure of course, yeah! We delivered it. No, honest. It’s not arrived? Ah, well that’s strange, honest we sent it, guv…”)

Right now T-Mobile know if my message has been delivered. And they bill me accordingly. Introduced home routing and T-Mobile won’t have a clue other if my message has arrived. They’ll still bill me, obviously, because Vodafone says they delivered the message…

The lack of transparency really bothers me. Particularly since we’ve only JUST got text messaging to the point where it’s more or less reliable for consumers to use.

The issue? Well, rumours — and they’re only rumours at the moment — indicate that many mobile operators in the UK and beyond are considering swapping to home routing.

Have you got a perspective? I’m going to look at this in a bit more depth over the next few weeks.

9 COMMENTS

  1. If I was on T-Mobile (academic point as this will *never* happen) I’d beg for Vodafone to be allowed to deliver the message..!

  2. You’re quite right – SMS is specifically designed to not work as you suggest. Implementing the system you describe, although commonplace in some territories (US, Hong Kong) is bloody stupid. It completely breaks delivery reports and other key functionality (bit like the iPhone ) and most of the claimed benefits can be performed synchronously without changing the transaction model.

    Where this is common is generally where there are completely different types of technology being used for delivery GSM vs CDMA vs TDMA vs iDEN vs Fixed-Line SMS (BT’s fixed line interconnects with the UK networks breaks the transaction model similarly) – where messages are generally queued and passed over IP rather than over the signalling network.

    MMS, unlike SMS, is designed with the transaction model where messages are passed to the destination network for delivery – this is one of the reasons why the rushed UK deployment of MMS is such a steaming pile of ….

    That said. I think you and that Wikipedia article might have completely the wrong idea about what “SMS home routing” is. There are a number of vendors who are now offering solutions which could be called “SMS home routing” but do not fuck with the transaction model. The transaction still happens between the originating SMSC and the handset but the message takes a different path across the international SS7 network; this is something that is specifically aimed at roaming subscribers.

    Lets take an example:

    You’re sending a message to Ed from your T-Mobile to his Vodafone.
    Ed’s currently in France, roaming on the SFR network.
    T-Mobile’s SMSC accepts your message, asks the Vodafone HLR where Ed is and Vodafone’s HLR will return Ed’s IMSI & the SFR MSC (switching centre) with which Ed is currently registered.
    T-Mobile’s SMSC then sends the message request to SFR’s MSC addressed to Ed’s IMSI.
    The SFR MSC pages Ed’s handset and then tries to deliver the message to him & reports the outcome to T-Mobile’s SMSC.
    T-Mobile’s SMSC then either knows that the message has been delivered or has responsibility for retrying it etc.

    Sounds fine right?

    One problem – this will only work if there is a roaming agreement between T-Mobile and SFR. If there isn’t then T-Mobile can’t send the message to SFR’s MSC. So even though T-Mobile might have a roaming agreement with another French network for their subscribers roaming in France then they also need to have one with SFR to be able to terminate messages to Vodafone customers roaming in France.

    France is a bad example since the UK ops all have great interconnects with the french networks, but in countries further afield, or those with new mobile networks then this can be a real issue.

    Home routing solves this:

    You’re sending a message to Ed from your T-Mobile to his Vodafone.
    Ed’s currently in France, roaming on the SFR network.
    T-Mobile’s SMSC accepts your message, asks the Vodafone HLR where Ed is and Vodafone’s HLR will return Ed’s IMSI & a Vodafone virtual MSC that knows where Ed really is.
    T-Mobile’s SMSC then sends the message request to the virtual MSC
    The virtual MSC then in realtime forwards on the request so the SFR MSC having re-written it so that it’s originates from itself (ie to SFR it appears that the message comes from Vodafone not T-Mobile)
    The SFR MSC pages Ed’s handset and then tries to deliver the message to him & reports the outcome to the virtual MSC
    The virtual MSC rewrites the request and passes it back to T-Mobile
    T-Mobile’s SMSC then either knows that the message has been delivered or has responsibility for retrying it etc.

    This is all done in realtime (it’s just like network address translation NAT in an IP network) and is invisible to both the T-Mobile SMSC and the SFR MSC. And it solves the problem – any country in which Ed can roam by definition must have a roaming agreement with Vodafone, so this allows T-Mobile to terminate messages to him whilst he’s there even if T-Mobile have no roaming agreement with the host network. Similarly other features (blocking by originator, spam filtering etc) can be implemented in realtime in the virtual MSC without breaking the transaction model.

    In my opinion these new technologies are a really good thing, but I agree that those that break the SMS transaction model (even given the crappy different-technology excuse) are rubbish and will continue to reduce reliability and consumer trust (it’ll keep the US SMS offerings well behind that offered in Europe for a long long time yet).

    Ewan, give me a shout if you wanna discuss further!

    Chris

  3. It’s been a long time since I played around with SMSCs, but here’s my thoughts.

    1) You’re still reliant on the destination network to report a delivery success. There’s nothing much to stop the destination giving a fake delivery report. Indeed, if you use SMS to landlines you will receive a delivery report when the message has been delivered to the destination’s SMSC, not to the recipient.

    2) Maintaining these interconnects is extremely expensive. If you have a million messages a second each trying for delivery from Operator A to Operator B, that’s a lot of wasted effort. Much better (easier and cheaper) to send the message and let the destination network deal with it.

    3) If you UPS or FedEx anything, you’d better believe that they’ll use a local contractor for the last mile! A courier will deliver to their nearest city and *then* give it to the local delivery boy.

    Of course, absent of a private key signed delivery report, you’re never going to know for sure whether it has been received. Even then, you don’t know it has been read or understood.

    This is something that I doubt will ever affect the customer except – we can hope – in lower operating costs and therefore lower bills.

    T

  4. There’s no need for a roaming agreement, the message can still be delivered. The networks don’t bother storing Global Title analysis for every network they roam with in their MSCs, if it’s not a UK PLMN or a ‘partner network’ where they have a direct/cheap interconnect, they just fire it off to BT or any other international SS7 gateway & let them route it.

    Home routing just sounds like another excuse for the networks to charge more for interconnect…

  5. Richard: BT International will not allow (smaller, anyway) PLMNs to send signals to PLMNs with which they don’t have an interconnection agreement – BT actually filter it.

    Furthermore BT don’t taking number portability into account when doing this. So if little network X has a roaming agreement with Y but not with Z then they won’t be able to terminate messages to Y’s subscribers if they’ve ported from Z.

    I don’t know whether BT will enforce that one the likes of Vodafone however…

    Chris

  6. As a messaging designer.. home routing is the clear answer to next gen messaging architectures, for multi presence / message access (carbon copy) / convergence of service. Also home routing will also allow the operator to eliminate spam, which is currently prolific between networks THANKS to BT’s lack of interconnect control

  7. I hope you’ve sorted out how home routing works by now. The way the SM Home Routing works, that I stand for, does not have any of the negative traits you are talking about here – there is no hand-over of responsibility to our home routing function. That’s not its purpose and it is definitely not needed. Its purpose is visibility by the terminating operator, fraud/spam/faking/spoofing checking and possibility to politely return a negative permanent response. All of this acts to improve reliability and possibility to be able to depend on SMS service without for example the spamming we’ve gotten used to have to deal with using e-mail. But, of course, I can’t talk for how other implementations work…

  8. If you want T-Mobile to deliver E2E then only SMS people on T-Mobile. If you want to SMS people who subscribe to Vodafone then expect it to traverse a few Vodafone network elements that T-Mobile is not resonsible for.
    Referring to T-Mobile as UPS and the Vodafone as some guy on a bike is way off the mark too. It’s like UPS handing your package over to FedEx. How could we live with that? Termination costs are also reconciled so it’s not like T-Mobile is making money off of your SMS termination. T-Mobile also receive SMSs too which means they bill Vodafone for delivery. Only the difference between the 2 is paid for. So if one SMS comes back to T-Mobile from Vodaofne (from any subscriber) you termination cost vanishes).

LEAVE A REPLY

Please enter your comment!
Please enter your name here

Recently Published

Is it time to subscribe to a printer service from HP?

Ever since my dad brought home an HP LaserJet printer (version 3, if memory serves), I have been printing with an HP. Over the...

What’s the best way of buying a phone today?

How did you buy your latest phone? I'm asking because I'm thinking about what I should be doing. When I was living in Oman, I...

MWC: What device highlights did you miss?

So, early last week I predicted that next to nothing from Mobile World Congress would break through into the mainstream media. I was right,...

How Wireless Will Pave the Path to Neobank Profitability

I'm delighted to bring you an opinion piece from Rafa Plantier at Gigs.com. I think it's particularly relevant given the recent eSIM news from...

An end of an era: Vodafone UK turns off 3G services

I thought it was worthwhile highlighting this one from the Vodafone UK team. For so long - for what feels like years, seeing the...

Mobile World Congress: Did the mainstream media notice?

I resolved this year to make sure I wrote something - anything - about Mobile World Congress, the huge mobile industry trade show taking...