Pinpoint SMS - International Usage

Dear forum,

using AWS Pinpoint we want to send and receive SMS to and from our customers. At the moment we are already using another 3rd party service to do so and plan to migrate to AWS (where all the rest is already hosted).

We are having international customers (so numbers have various country codes) and started buying two long codes: one for Germany (+49) and one for Netherlands (+31).

While testing Pinpoint, with a few German numbers (+49), we noticed the following:

• Outgoing, we can send SMS from Pinpoint to our German numbers using the German long code as "originationNumber"
• Incoming, we can send SMS from our German numbers to Pinpoint when sending to our German long code (SMS is handed over to SNS reliable)

However:

• Outgoing, when we use the Netherland long code as "originationNumber" to send SMS to German numbers, we always receive SMS from the German long code (so not the explicitly specified Netherland long code). It does not matter if we do it via API or test message UI in Pinpoint.
• Incoming, when we send from a German number towards the Netherland long code, the incoming SMS is not received at all.

We know from our currently used 3rd party service for SMS handling, that international roaming can be tricky. While sending works reliable there internationally (so from +49 to a +31 number as example), they also have issues with receiving sometimes.

Questions:

• why can't we send from the +31 number to a +49 number, although we explicitly specified the "originationNumber"?
• is it expected that pinpoint can't receive an SMS from a number with a different country code?

Greetings

Markus