There are two ways to verify the delivery of SMS messages.
When a message is send using the SMPP protocol, the provider returns a message reference. Using this reference, we can query the provider for the delivery status of this message. This is done by sending a 'query_sm' PDU to the provider. If the message reference is known by the provider, it responds with a 'query_sm_resp' PDU. This packet holds the status of the message. This can be one of the following values:
|0||SCHEDULED||The message is scheduled for later sending.|
|1||ENROUTE||The message is enroute.|
|2||DELIVERED||The message was successfully delivered.|
|3||EXPIRED||The SMSC was unable to deliver the message in a specified amount of time. For instance when the phone was turned off.|
|4||DELETED||The message was deleted.|
|5||UNDELIVERABLE||The SMS was unable to deliver the message.For instance, when the number does not exist.|
|6||ACCEPTED||The SMS was accepted and will be send.|
|7||UNKNOWN||Unknown error occured.|
|8||REJECTED||The message was rejected. The provider could have blocked phonenumbers in this range.|
|9||SKIPPED||The message was skipped.|
The disadvantage of this method is, that you have to poll once in a while to get the current message status. When a lot of messages are enroute for a couple of hours, this will cause heavy data traffic. Most providers recommend you to request delivery reports instead of querying, because there is only data sent by the provider when the status of a message has changed. Therefore, the 'query_sm' method is not supported by most SMPP providers.
The best way to check the status of each message sent, is to ask for delivery reports. This can be done by setting the 'registered_delivery' flag of the 'submit_sm' SMPP PDU. This parameter can have one of the following values:
|0||Do not send delivery reports|
|1||Always send delivery reports|
|2||Send delivery report in case of an error|
|3||Send delivery report only when message is delivered|
By setting this value to '1', the provider will send a delivery report to the client every time the status of this message changes. You can set this value per message.
The delivery reports are sent to the client using the 'deliver_sm' packet. This is the same packet as used to deliver incoming messages. To detect whether a 'deliver_sm' is a delivery report or a message, you have to check the 'esm_class' field. If bit 2 of this byte is set ( 0x04 ), it is a delivery report. To use delivery reports, you have to setup a transceiver connection to the SMPP provider, because you are going to send and receive messages. The delivery status is encoded in the 'short_message' field as an ASCII text message. This format is product specific, but the following format is used by most SMPP providers:
id:c449ab9744f47b6af1879e49e75e4f40 sub:001 dlvrd:0 submit date:0610191018 done date:0610191018 stat:ACCEPTD err:0 text:This is an Acti id:7220bb6bd0be98fa628de66590f80070 sub:001 dlvrd:1 submit date:0610190851 done date:0610190951 stat:DELIVRD err:0 text:This is an Acti id:b756c4f97aa2e1e67377dffc5e2f7d9b sub:001 dlvrd:0 submit date:0610191211 done date:0610191211 stat:REJECTD err:1 text:This is an Acti id:bd778cd76ae9e79da2ddc8188c68f8c1 sub:001 dlvrd:0 submit date:0610191533 done date:0610191539 stat:UNDELIV err:1 text:This is an Acti
|id||The message reference of the message.|
|sub||Sub-ID, not used.|
|dlvrd||Value '1' when the message has been delivered, if the message is still pending '0'.|
|submit date||Submission date and time.|
|done date||Date and time the status has changed, or message delivery time when stat is set to 'DELIVRD'.|
|stat||Current status of the message.|
|err||Additional error code, provider specific.|
|text||Part of the original message text.|
NOTE: The message reference returned in this delivery report can be returned in hexadecimal or decimal format. This varies per provider. You have to specify the delivery report format your provider is using, by setting the 'DeliveryReportFormat' property to 'asSMPPDELIVERYREPORTFORMAT_HEX' for hexadecimal (default) or 'asSMPPDELIVERYREPORTFORMAT_DEC' for decimal.
When using SMPP version 3.4, sometimes the message has some optional parameters (TLV's) attached containing the message state, message reference and a network error code. Please refer to the SMPP version 3.4 documentation on how to use these TLV's.
The SMS and MMS Toolkit (SMS API) only supports the second method (waiting for delivery report) to retrieve the delivery status of a message.
To use this method you have to connect with the 'SystemMode' property set to 'asSMPP_MODE_TRANSCEIVER'. Because the connection is setup for both sending and receiving, the SMS component will be listening for incoming delivery reports and store them in its internal cache memory.
Once the connection has been established using the 'Connect' function, you can submit messages. Please note, that to request a delivery report for a particular message, you should have the 'RequestDeliveryStatus' property of the SmsMessage object set to 'TRUE' or '1'. If a message is accepted by the provider it will return the reference number for this message.
Now you can call the 'QueryStatus' function. The QueryStatus will check the internal cache of the SMS component if there is a delivery report available for the given message reference. If the operation was successfull ( LastError = 0 ), it will return a SmsDeliveryStatus object. This object contains the following properties:
|Status||The status of the message. See the above table for possible values|
|StatusDescription||Textual representation of the returned status|
|StatusCode||Operator dependent additional info about the status of the message, or cause of the error|
|IsCompleted||Indicates whether the message is in its final state. If this property is FALSE, the provider is still rertying|
|StatusCompletedTimeSecs||Time in seconds after 1/1/1970 that message reached its final state|
|StatusCompletedTime||Time (formatted string) that message reached its final state|
|ProviderReference||The original reference returned by the provider. The message reference returned on the Send call is an internal message reference generated by the toolkit itself|
The following VBScript code sample demonstrates how to use delivery reports with the SMS and MMS Toolkit:
Option Explicit Dim objSmpp, objMessage, objStatus, objConstants Dim strRef, strStatus, i ' Create Objects Set objSmpp = CreateObject ( "ActiveXperts.SmsProtocolSmpp" ) Set objConstants = CreateObject ( "ActiveXperts.SmsConstants" ) Set objMessage = CreateObject ( "ActiveXperts.SmsMessage") ' Set Provider Settings objSmpp.Server = "smpp.activexperts-labs.com" objSmpp.SystemID = "AX008" objSmpp.SystemPassword = "812056" ' connect as Transceiver objSmpp.SystemMode = objConstants.asSMPPMODE_TRANSCEIVER objSmpp.Connect If ( objSmpp.LastError ) Then WScript.Echo "Connect failed: " & objSmpp.GetErrorDescription ( objSmpp.LastError ) WScript.Quit End If objMessage.Data = "delivery report test" objMessage.Recipient = "+31647134226" objMessage.RequestDeliveryStatus = True ' Send the message strRef = objSmpp.Send ( objMessage ) If ( objSmpp.LastError ) Then WScript.Echo "Send failed: " & objSmpp.GetErrorDescription ( objSmpp.LastError ) objSmpp.Disconnect WScript.Quit End If ' Store message reference WScript.Echo "Message submitted, ID = " & strRef For i = 1 To 20 WScript.Sleep 5000 ' Query the delivery status Set objStatus = objSmpp.QueryStatus ( strRef ) If ( objSmpp.LastError = 0 ) Then WScript.Echo "Message status after " & i * 5 & " seconds: " & objStatus.StatusDescription If ( objStatus.IsCompleted = True ) Then End Loop End If Next objSmpp.Disconnect WScript.Echo "Ready."
This VBScript will generate the following output:
Message submitted, ID = 00000E73 Message status after 5 seconds: Scheduled Message status after 10 seconds: Enroute Message status after 15 seconds: Enroute Message status after 20 seconds: Delivered Ready. Ready.