SMS wont send international messages

Provider: Claro Peru.
Using BB OS 5.0.0.411

I can receive and send all internal SMS messages
I can receive all international SMS messages
I can NOT send any international SMS messages

Claro has checked their settings and said there is no block

I installed IM+ some time ago because I USED to be able to send international SMS except to Ethiopia, IM_ was the only one that would get through to Ethiopia - no idea why. Now that has the same problem

I presume this is a fault between Claro Peru and me using the 5.0.0.411 but am not sure.

Is there a work around?

Thanks