A concatenated short message service is used to beat the maximum on the number of figures that are able to be sent in a single SMS text message transmission (usually 160 characters). This technique allows the sending device to split the long message into smaller ones that get recombined at the end when being received. Each smaller message is charged singly.
Due to this feature, the whole sms text message appears to end user as a complete long text message (a concatenated SMS message). There are networks that do not support Concatenated SMS and in this case every smaller message is delivered as a single SMS text message.