Trying to debug and help my fellow aussie friends who use Telstra mobile in Australia.

I am on skinny but other person having issues (the primary family person here in NZ of Friends) uses spark.

They can receive our txts fine and no delay. But replies or new messages to us either not received here in NZ or a very long delay. Last txt took 6 days. Was working fine they say about 3 months ago.

Apparently they can txt to vodafone / 2degrees mobiles without any issues.

I strongly suspect this is a Telstra routing issue and sparks hands will be tied on what they can do.

Any advice would be appreciated.