I tried sending a long SMS using another Telco number. I received it in the back-end as 2 separate messages with no direct way to link the two sub-messages together. Both had different 'messageId', and 'numberOfMessagesInThisBatch'=1.
I tried sending with a Globe number and at least that one had 'numberOfMessagesInThisBatch'=2.
The docs say that a multi-part SMS will be received with these additional parameters:
Parameter | Description
multipartRefId | ID of multi-part message
multipartSeqNum | Sequence of multi-part message
But this doesn't seem to be true in my case.