GLS US (formerly GSO) Integration

GLS US — the carrier formerly known as GSO — is connected directly using your own shipper account, so rates and labels come from your contract and are billed to your GLS account with no aggregator per-label fee on top. Two limits are stated here because they are safety facts rather than marketing caveats. First, this connection is US DOMESTIC ONLY: GLS does rate its international products, but buying those labels needs line items and customs data this connection does not carry, so an international lane is refused at the rate rather than at the counter, where you would already have quoted a buyer. Second, it is PRODUCTION ONLY: GLS publishes no sandbox, so every label bought through this connection is real and billable to your account. TackQuote refuses a connection set to "test" outright rather than quietly pointing it at the live host — a seller who selects test specifically to avoid spending money must never end up buying real postage instead. Authentication is its own scheme: a username and password travel as request headers and are exchanged for a short-lived token that every later call carries, which is neither OAuth nor HTTP Basic and is described as what it is.