As I know concatenated sms are split in GSM handset and delivered to network. Does GSM standard talk about order of these packets? Will it be always sent in order? That is first sequence packet first and next later?
My questions regarding this. 1. Does SMPP talk about order of long sms segments? Like is it possible for SP to get out of order messages? 2. Does GSM handset deliver long messages always in order or not?
"long sms" officially known as concatenated sms can and will turn up in any order. Therefore the receiving device / system must be able to cater for this. Concatenated sms come in the form of multiple sms. Encoded within is the part number and the total number of parts for the concatenated sms (you can search for information on the "UDH - User Data Header" to get more information).
So answering your questions:
1) There is no ordering in the sending / receiving of concatenated sms. Only information within each concatenated sms part which says which part it is and how big the complete concatenated sms is.
2) GSM handsets tend to send out in order. The order is lost usually during the store and forward process on the SMSC side. On a side note GSM handsets when receiving a concatenated sms build the sms once all parts are received.