BT SMS Gateway - Frequently Asked Questions
The following answers are provided for the current release of SMS gateway application software which is
Release 5.0.
In what follows, short-code, originator and source address are used interchangeably to mean the same
thing.
1. The SMS Gateway returned “Sent” but the message did not arrive on the phone.
Why?
There are a number of reasons why this might happen some possibilities are:

The destination phone was switched off or out of coverage or its SMS storage capacity limit was
reached (memory full) when the message was sent and remained so for longer than the specified
validity period of the message or the default validity period of the mobile network via which the
message was sent.

The destination number is subscribed to a mobile network other than the one via which the
message was sent and these two networks do not have an SMS interconnect agreement in place.
This is more likely if the destination number is not a UK number or the originator is a reverse billed
short-code.

The message was rejected by the mobile network because the destination phone number was
deemed to be invalid (e.g. digit missing, incorrectly formatted, number is on another network
without interconnect agreement).

If you are sending a reverse billed message to a pre-pay number it is possible that there is
insufficient credit on the account to cover the cost of the message. On some networks this will not
result in an explicit rejection and the message will expire within the mobile network infrastructure if
the pre-pay account is not topped-up before the network’s default validity period is reached.

The message has been deleted by the mobile network to reduce congestion.

We have seen some cases where handsets, particularly Smartphone and PDA type devices,
cannot display SMS messages from alphanumeric originators.
2. What format should the destination number be in ?
The preferred format is the international number string without the 00 or + sign.
For example, a UK number should be sent as 447xxxxxxxxx, an Irish number as 3538xxxxxxxx
However, the SMS Gateway does some checks. If the number begins with 07 it is assumed to be a UK
number and 07 is changed to 447. All spaces and – characters are removed from the received number
string. If the number begins with 01 or 02 this is assumed to be a UK fixed line number and these will be
changed to 441 and 442. All other numbers are passed unchanged to the mobile networks.
3. How do I know which network the message was sent via ?
Within the SMS Gateway, the routing policy is based on a combination of the parameters that are supplied
in the request from the customer’s application. There are also commercial considerations that can
determine which mobile network the messages are actually sent to.
If your application supplies, a from (http GET) or <oa> (http POST/XML) parameter in the range
212300xx then these messages are routed via O2 or T-Mobile depending on monthly volume of
messages your application is sending.
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BT Managed SMS Gateway – Frequently Asked Questions
If your application supplies an alphanumeric string as the from (http GET) or <oa> (http POST/XML)
parameter then these messages are routed via O2 or T-Mobile depending on monthly volume of
messages your application is sending.
If your application supplies a four or five digit short code, like 81234, as the from (http GET) or <oa>
(http POST/XML) parameter, AND, BT has not asked you to supply the smsc parameter, then these
messages are routed via Vodafone or T-Mobile depending on monthly volume of messages your
application is sending.
For reverse billing services to work correctly the message must be sent via the network to which the
phone number is subscribed. Obviously this means that messages sent using these originators to
numbers other than the UK networks of O2, Orange, T-Mobile (inc Virgin Mobile), Vodafone or 3 will not
be delivered.
If your service is reverse billing the recipients of the messages then you will be providing a four or five digit
number, like 81234 or 61234, as the from (http GET) or <oa> (http POST/XML) parameter. BT will have
also provided you with a list of possible values that can be supplied as the smsc parameter. The smsc
parameter must be set correctly for each message depending on the destination network of the mobile
phone number.
You can capture the network information from a mobile originating message and use this when
responding to these messages to ensure that you send via the correct network. See the HTTP
Programmer’s guide for details of the format of MO messages and the location of the smsc parameter.
If you connect to the BT SMS Gateway using SMPP then you can only send free-to-receive messages
and BT will route your messages to Vodafone, O2 or T-Mobile depending on the source-address (shortcode) you are using and the monthly volume of messages your application is sending.
The SMS Gateway currently has direct connections to the following networks in the UK only; O2, Orange,
T-Mobile, Vodafone, 3 and the BT Fixed-Line SMS Service.
4. If all my messages are sent via O2 or Vodafone or T-Mobile will they reach phones
that are on other networks
As long as you are not using a reverse billed short-code, and the destination is UK number, the answer is
yes.
For international destination numbers see the next question.
5. Can I send to international numbers ?
Yes, but there are restrictions and limitations.
Messages can, generally speaking, be sent to international destination numbers but only using shortcodes (originators) which are not reverse billed or premium rate. It is not possible for the recipient to
reply to these messages but delivery receipts are usually returned.
Ultimately, whether the message gets delivered or not depends on whether there is an SMS interconnect
agreement in place between the mobile network via which the message was sent and the destination
mobile network.
For this reason, delivery of messages to international (i.e. non-UK) numbers and the generation of any
resulting delivery receipts cannot be guaranteed.
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BT Managed SMS Gateway – Frequently Asked Questions
It is unlikely that messages will be delivered to numbers that are subscribed to non-GSM mobile services
that are prevalent in North, South and Central America and South East Asia
6. How do I find out what’s happened to a message once sent to the BT SMS Gateway
If you want to know the progress of your message through the gateway and the mobile network then you
can request delivery notifications.
To do this you must set the dlrmask parameter and provide a URL, to which the SMS Gateway will use
HTTP GET to return these notifications, in the dlrurl parameter. A notification will be returned to your
application with the result of the attempt to send the message into the mobile network. If this was
successful then a subsequent notification will be returned with the final status of the message – e.g.
delivered to handset.
This is described in detail in the HTTP programmer’s guide.
NOTE: the implication is that you have to run a web server and your Firewall can be configured to allow
incoming http or https from the BT SMS Gateway in order to receive these notifications.
If your application connects using SMPP then just set the registered_delivery_flag in the submit_sm.
7. How long should it take for the message to reach the phone ?
Normally messages will be delivered within about 10 seconds but delays in the mobile networks can result
in longer delays and, in rare cases, when there is heavy demand on the mobile networks, it may take
several hours (e.g. New Year’s eve).
SMS is a store and forward service (like email) and is therefore prone to queuing delays. Queues can
develop in the BT SMS Gateway and in the mobile networks. Queues in the mobile networks are beyond
our control.
Mobile networks do not provide service level agreements for delivery of SMS messages and because of
this neither does BT.
8. Why do I receive Notifications with status of expired when I didn’t set an expiry time
or validity period ?
If you requested status notifications but did not set an expiry time or validity period then the mobile
network via which the message was sent will apply their own default value. These are currently:
O2 UK
7 days
Orange UK
21 days
Vodafone UK
3 days
T-Mobile UK
3 days
3 UK
tbc
BT Fixed
2 days
9. Can recipients reply to messages I send them ?
Yes, but there are limitations and restrictions. See Q16 for details of how to set this up.
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BT Managed SMS Gateway – Frequently Asked Questions
10. I sent a message but it took hours/days to arrive. Why ?
See Question 7.
Also check that the phone was not switched off or out of coverage or its memory was not full when the
message was initially sent.
A reverse billed message to a pre-pay number may have been queued in the mobile network until there
was sufficient credit on the account to cover the cost of the message.
11. How do I send binary SMS messages (logos, ringtones, etc.) ?
The udh parameter must be correctly set in the http POST/GET and the text parameter must be the
correctly encoded data string. If concatenated messages are required then each must contain the correct
udh with information relating to the message number and its sequence.
An example of a Nokia format ringtone is shown in the following http GET
http://www.messaging.bt.com/cgibin/sendsms?username=<your_username>&password=<your_password>&from=21230000&to=44712
3456789&udh=%06%05%04%15%81%00%00&text=%02%4A%3A%51%D1%95%CD%D0%04%00%1B
%20%55%05%90%61%05%60%55%85%50%54%85%40%82%08%49%90%00%00&coding=1
See the http programmer’s guide for a more detailed explanation and references to relevant GSM
standards documents.
If your application connects using SMPP then you need to set the appropriate data_coding value and
encode the short_message as necessary.
12. I sent a binary message but it did not display correctly on the phone. Why ?
There are a number of possible reasons for this:

The handset does not support the form of encoding you used in the message. For example you
sent a Nokia Smart Message format message to a Sony Ericsson handset.

You have not encoded the udh correctly or have not set the coding parameter correctly

The binary data is not correctly encoded

For a concatenated message ensure that the udh is correct in each of the messages.

Concatenated messages cannot currently be sent to O2 numbers using reverse billed originators
(short-codes).

Many phones are not able to re-construct concatenated messages so they may be displayed out
of sequence.
Check the specifications relating to the format and encoding of the binary message you are sending, e.g.
Nokia Smart Messaging, EMS or other handset manufacturer specific formats.
13. I sent a Flash message but it did not display on the phone as I expected. Why ?
Check that you have set the mclass parameter in the http POST/GET correctly – it should be 0.
Not all handsets support Flash (immediate display) messages and those that do may not all deal with
them in the same way. Try sending to various handsets.
14. Some characters did not display correctly on the receiving handset. Why ?
Not all handsets support all characters and will employ some form of substitution if they do not support a
particular character. This is particularly true on older handsets and of the extended GSM alphabet
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BT Managed SMS Gateway – Frequently Asked Questions
characters | ^ { } [ ] ~ \ €. For example an Ericsson T39m or Nokia 3310 will display ¡^ ( ) < > = / e if you
send it this character string.
15. Some recipients report receiving the same message more than once. How can this
happen ?
We have had a few cases where the mobile network operator has informed us that the handset is not
acknowledging the SMS (even though it has received and displayed it) so the mobile network keeps trying
to deliver the message.
For example, there is a known problem with earlier versions of the Ericsson T68i which prevents it from
acknowledging SMS messages that have an alphanumeric originator. This results in the mobile network
constantly re-trying. There is apparently a software upgrade available to cure this problem – check with
your retailer or service provider.
If this happens we need to inform the mobile network operator and they will delete the message.
Network congestion between the BT SMS Gateway and the mobile networks can also result in response
timers expiring causing a duplicate messages to be sent.
16. How can an application receive SMS messages from mobile phones ?
You need to contact your BT account manager and request the mobile originating SMS service. You will
be provided with a short-code that is common across all UK mobile networks which people will use to
send SMS messages to your application.
Note that it is not currently possible to receive messages from non-UK mobile networks.
If you connect to the SMS Gateway using http and wish to receive SMS messages from mobile phones
you must supply a URL which we can use to send these messages to you using http GET or POST/XML.
Please refer to the http programmer’s guide for details.
If your http application is not available for some reason then the SMS Gateway will put your message into
a retry schedule.
NOTE: the implication is that you are running a web server and your Firewall can be configured to allow
incoming http or https from the SMS Gateway. Obviously your application must also be able to process
the http sent by the SMS Gateway.
If you connect to the SMS Gateway using SMPP then MO messages will be sent to your application in a
deliver_sm operation.
It is also possible for the SMS gateway to send messages on a single short-code to different applications
(URLs) based on the first word or words of the text message. This is known as keyword routing and can
be an effective way to share a short-code across multiple applications. If you want the SMS Gateway to
manage the routing to different applications then the keyword(s) and corresponding URL(s) must be
specified at the time of order and any additions or changes to these must be requested from BT.
There may be additional charges for this service
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BT Managed SMS Gateway – Frequently Asked Questions
17. I tried to send a message but there was no response from the BT SMS Gateway –
what is wrong ?
If your application is sending using the http interface then the HTTP Programmer’s Guide lists a number of
potential HTTP level error messages that could be returned to your application. These will be returned as
HTTP error codes (e.g. 403 – Forbidden) with some accompanying text.
Depending on the error code received you may want to check some of the following:

You are sending to the correct URL as per the HTTP Programmer’s Guide

Your application has access through your corporate Firewall to the internet on TCP port 80 (http)
and/or port 443 (https).

Have you changed your application server’s Public IP Address but not told the BT SMS support
team. Note that this could happen if your internet access employs Network Address Translation
and the settings for this have been changed at your Firewall or Proxy server.

You are sending the necessary parameters and have formatted them correctly as per the
programmer’s guide and any advice from the BT SMS support team

You have supplied the correct username and password in the HTTP GET/POST.

If you are able to perform a traceroute operation from your application server, through your
corporate Firewall then please do this and supply to the BT SMS support team.
If your application is sending using SMPP then you need to check the SMPP error that is being returned.
If your SMPP bind or submit_sm messages are timing out then you need to check the following:

Can you telnet from your application server to the BT SMS Gateway on the TCP port number you
have been asked to use for the SMPP connection. If you get a timestamp and “connected” then
the underlying network connectivity is available.

Are you using the correct SystemID and Password.

Your application has access through your corporate Firewall to the internet on the TCP port
number you have been asked to use for the SMPP connection.

Have you changed your application server’s Public IP Address but not told the BT SMS support
team. Note that this could happen if your internet access employs Network Address Translation
and the settings for this have been changed at your Firewall or Proxy server.

If you are able to perform a traceroute operation from your application server, through your
corporate Firewall then please do this and supply to the BT SMS support team.
END OF DOCUMENT
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