Never managed to receive US originated SMS on my 2D phone when roaming in the US

Forums › 2degrees (including Slingshot, Orcon, Flip, Stuff Fibre, MyRepublic, 2talk and Vocus) › Never managed to receive US originated SMS on my 2D phone when roaming in the US

lchiu7

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#75218 14-Jan-2011 23:25

This is a strange one. When in the US I carried two phones, one with my 2D SIM and one with a local SIM.

I could never receive SMS on the 2D phone if it originated from the US (say just texting from a US phone) or any gateway for that matter but SMS originating from NZ seem to be fine as evidence by SMS from ASB Bank for their SMS authenticaion for banks transfers and timely reminders from 2D about bills due to be paid.

This is on a ported VF number if that makes any difference.

Any ideas whey this would be the case?

Thanks

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keewee01

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#427338 15-Jan-2011 08:41

lchiu7 - there is a significant amount written on this in the forums already. There is a thread The Short Message Service pinned at the top of the forum where salty has gone into very significant detail on this issue. Just search and you'll find heaps more on the issue too.

lchiu7

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#427581 16-Jan-2011 11:12

A lot of very technical information but hardly useful for the regular mobile customer wondering why their messages are not going through.

As an aside last year at the same time when I was visiting the US, on a VF SIM, I experienced no problems sending and receiving SMS on my phone when roaming in the US, either from people in NZ or people on US networks.

That is why I was so surprised and somewhat annoyed when on my 2D SIM I experienced these problems I described.

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SaltyNZ

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#427588 16-Jan-2011 11:31

lchiu7: A lot of very technical information but hardly useful for the regular mobile customer wondering why their messages are not going through.

Hi there,

I'm sorry you're having these problems with the service. I'm also sorry my very technical explanation wasn't helpful for you. However, I'm afraid that the problem is very technical, and complex, and there is no simple layman's explanation. Only the warning on our website that tells you that you may have problems receiving international SMS with a ported number, especially one that was ported from Vodafone (and the reason for that is also very technical).

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keewee01

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#427905 17-Jan-2011 10:45

lchiu7: A lot of very technical information but hardly useful for the regular mobile customer wondering why their messages are not going through.

As an aside last year at the same time when I was visiting the US, on a VF SIM, I experienced no problems sending and receiving SMS on my phone when roaming in the US, either from people in NZ or people on US networks.

That is why I was so surprised and somewhat annoyed when on my 2D SIM I experienced these problems I described.

Yes, very technical, but towards the bottom of the thread it wraps it up in a nutshell.

lchiu7

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#427917 17-Jan-2011 11:01

keewee01:
lchiu7: A lot of very technical information but hardly useful for the regular mobile customer wondering why their messages are not going through.

As an aside last year at the same time when I was visiting the US, on a VF SIM, I experienced no problems sending and receiving SMS on my phone when roaming in the US, either from people in NZ or people on US networks.

That is why I was so surprised and somewhat annoyed when on my 2D SIM I experienced these problems I described.

Yes, very technical, but towards the bottom of the thread it wraps it up in a nutshell.

True enough but the bottom line for me is, at the moment expect SMS problems if you have a ported VF number on 2D and want to receive SMS from US senders when in the US (probably would apply to the UK also).

It would be good to have all SMS forwarded to another number done automatically but I don't know how to do that. It seems easier enough to divert calls though.

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SteveON

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#427920 17-Jan-2011 11:06

If your number is ported then expect issues, if your number is fully 022 then it should be sweet.

SaltyNZ

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#427932 17-Jan-2011 11:26

lchiu7:

... to receive SMS from US senders when in the US (probably would apply to the UK also).

At the risk of labouring the point, where you happen to be standing in this case is much less relevant than the fact that your number is ported.

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lchiu7

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#427958 17-Jan-2011 12:10

SaltyNZ:
lchiu7:

... to receive SMS from US senders when in the US (probably would apply to the UK also).

At the risk of labouring the point, where you happen to be standing in this case is much less relevant than the fact that your number is ported.

Understand that. Still annoying. Now if there were a way to divert all SMS to some other place, that would go somewhere towards making it less of a hassle. I assume that when somebody sends a SMS to a 2D number that has been ported, and the phone is roaming, 2D receives it locally(?) but has no way of forwarding it to the phone? Or am I wrong here?

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allan

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#427967 17-Jan-2011 12:19

lchiu7: It would be good to have all SMS forwarded to another number done automatically but I don't know how to do that. It seems easier enough to divert calls though.

Is it actually possible to forward SMS messages to another number?

SaltyNZ

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#427991 17-Jan-2011 13:10

lchiu7: Or am I wrong here?

Yes.

From my other thread, the upshot of which is "most likely the other operator's SMSC delivers direct to your handset":
Delivering a Message - SS7
The SMSC contains message routing tables. Let's assume the destination is valid - we will deliver it successfully in this example - and that the routing tables say SS7 delivery is required. In NZ, we do not use SS7 delivery for national interconect messages. This is mainly because Telecom's CDMA network had only limited support for MAP until recently, and it was easier to use a different protocol, SMPP, which is pretty technology-agnostic. SS7 delivery is used to deliver within the network though (i.e. 2degrees to 2degrees, Vodafone to Vodafone, Telecom to Telecom).

Step 1 - Where are you?
The essence of a mobile network is that you are, in fact mobile, and therefore not always in the same place. The go-to element for location information is the HLR, the Home Location Register.

The HLR maintains all the static information about your subscription, keyed on IMSI. (Not MSISDN, like I said, the mobile network really only cares about IMSIs). In addition to the static info, it also includes a piece of dynamic info, the VLR address (Visitor Location Register).

Your subscriber data is always stored in the HLR. A copy is stored in the VLR attached to the MSC you're currently attached to. This means that your static info is always here at Khyber Pass in our HLR, but the realtime copy might be in Vodafone, or Telstra Australia, or AT&T USA, or in whoever's network you currently happen to be standing.

The SMSC needs to know the VLR address. But the problem is, it doesn't even know your HLR address. So we do some trickery.

The SMSC constructs a new MAP message called SRI_SM (Send Routing Info for Short Message). The SRI_SM contains the following info:

SCCP - CgPty = SMSC GT, CdPty = MSISDN, <-- trickery CdPty SSN = 6 (HLR)
MAP - TP Data CdPty MSISDN

At some point along the way an STP, or another node performing an STP function (perhaps an MSC) sees the magic combination CdPty = MSISDN, SSN = 6. The STP has a translation table that turns MSISDN prefixes (e.g. 6422) into HLR addresses. It substitutes the HLR address as the CdPty address and forwards the message on.

Eventually it will arrive at the HLR - which may be in the same network, or elsewhere in the world. The HLR will send back a response with the following information:

SCCP - CgPty = HLR SSN = 6, CdPty = SMSC GT, SSN = 8
MAP - CdPty IMSI, CdPty VLR address

Note, you can also deliver messages in the packet network via the SGSN instead of the MSC/VLR, but it's virtually identical as far as the SMSC is concerned.

Now the SMSC knows where you are and can proceed to deliver the message.

Step 2 - Message Delivery
The SMSC constructs a new MAP message, MT_FSM, which contains the following information:

SCCP - CgPty = SMSC GT, CdPty = VLR GT, SSN 8 (MSC)
MAP - TP Data - Originating TON, NPI, MSISDN; Destination TON, NPI, MSISDN; flags; message text

The SMSC will deliver this message into the SCCP network whereupon it will eventually arrive at the correct MSC/VLR. The MSC will start some radio paging procedures to establish contact with the handset (fluffy cloud) and deliver the message. The handset will ACK the message to the MSC, and the MSC will ACK the message to the SMSC.

Should the SMSC fail to receive an ACK in a timely manner, or receive a NACK for some reason, the message will be returned to the queue to be retried later. In the specific case that the MSC reports that the handset has powered off, the SMSC sends another MAP message, Set Message Waiting Data, to the HLR, to request that the HLR inform it when the handset reattaches.

This is why you begin to receive queued messages within a minute or so after powering on your handset.

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These comments are my own and do not represent the opinions of 2degrees.