International SMS is not a service so much as a description of what happens when your recipients are in more than one country. Each destination is its own market, and almost everything you might assume is global turns out to be per country.
Why is one destination more expensive than another?
Because the cost of terminating a message on that network is different, and it dominates everything else.
A message reaching a handset is delivered by a carrier in that country, and that carrier charges for it. Those rates are set market by market, shaped by local competition, regulation and the number of intermediaries between your provider and the network. The result is a spread far wider than people expect: neighbouring countries can differ by an order of magnitude.
Distance has nothing to do with it. Nor does your provider's own margin, which is the smaller component. The rate is mostly a property of the destination's own market, which is why no provider can flatten it into one worldwide price without overcharging most of your traffic.
Current rates per country are published on the SMS destinations page and the pricing pages, which read them from the source. They are not repeated here, because a rate copied into prose is wrong the moment it changes and nothing tells you.
What else changes between countries?
More than the price, and the rest of it is what actually breaks sends.
- Which sender types are carried. Alphanumeric senders work in many countries and not in others; some destinations expect a local number. Which sender type should I use covers the choice.
- Whether the sender must be registered first. Bird's country policy records, per destination, whether a sender has to be registered before it can be used. What is sender ID registration covers what that involves.
- What consent model applies. Opt-in, opt-out or double opt-in is a property of the destination rather than a policy you choose. Which SMS consent model applies covers it.
- When you may send. Some destinations restrict messaging hours in local time. What are SMS quiet hours covers them.
- How fast you may send. Throughput ceilings are per destination and per sender type. What is SMS throughput covers both limits.
All five are published per destination alongside the rates, which is the useful thing: they are data you can read before you send rather than rules you discover afterwards.
Do I need to do anything to send internationally?
Enable the destination, and check what it carries.
Bird gates sending per destination, so a country has to be enabled on your account before traffic reaches it. That is a deliberate control rather than an obstacle: it means an accidental send to an expensive market does not happen, and it is the main defence against SMS pumping, where the cost of a fraudulent send is the point of the attack.
After that, the preparation is per destination rather than general. Confirm the sender type you plan to use is carried, register it if the destination requires registration, and check the consent model against how you collected the list.
How should I plan a multi-country send?
By treating it as several sends that happen to share a body.
A campaign to twenty countries is twenty sets of rules, rates and throughput ceilings. The parts that vary are exactly the ones above, and the parts that do not vary are the body and your list hygiene.
Two consequences worth building around. The send finishes when the slowest route finishes, not when the fastest does, so bulk send planning should use the slowest. And cost is dominated by which countries are in the list rather than by how many recipients are in it, so a small tail of expensive destinations can outweigh the bulk of your volume.