During testing of a product recently, I was sending SMS's with custom SenderIDs through a New Zealand based SMS provider via API.  However these custom SenderIDs were not showing up on Telecom phones.   I require custom SenderID's as the product relies on the reply going back to the originating number - and each customers has their own number.

The local provider replied
"Recently (approx 3~4 months ago), Telecom started filtering the Sender IDs on messages arriving on their network.

They culled this down to specific Sender IDs only (authorised senders and those using Short Codes).
This means we are now unable to provide the Sender ID option for TXTs sent to the Telecom network, as these TXTs must now originate from our premium route connections to Telecom.

Any TXTs sent to the Telecom network will originate from one of our pooled numbers (the 021 and 022 numbers you saw).

.....

This is unavoidable, as any custom Sender ID will fail to deliver to a Telecom handset.
"


Does anybody know of Telecom partner where I am able to set the SenderIDs for each message (using a API?).

I guess this is the risk of building a product that relies on the infrastructure of others. One change and a years work down the drain :-)

Sorry if this has been discussed before, spent several hours looking but found nothing. 


Thanks for any feedback

Michael