If you have ever priced up a move off SPS Commerce or TrueCommerce, you probably got as far as the cutover and stopped. Not because of the contract. Because of the picture in your head: switch everything over one weekend, then find out on Monday which retailer's orders didn't come through.
That is the right thing to be worried about. It is also avoidable.
What full-service EDI is quietly doing for you
A full-service provider does several jobs quietly enough that it is easy to forget they are jobs. Two of them matter most when you leave.
The first is the connection. Documents have to get from your partners to you and back, through a network, a direct link, or both, under an identity your partners recognise.
The second is the maps. Every partner's documents have to be turned into something your system understands, and whatever your system produces has to be turned back into what each partner expects.
There is a third that people forget until it bites. Retailers revise their requirements, and on a full-service plan keeping the maps current is usually someone else's job.
Leave, and all of it comes back to you. The jobs are not equally hard.
The connection is usually the easy part
Getting connected is the part that has genuinely become cheap. Networks interconnect, direct links are well understood, and none of it is exotic.
The one thing worth checking early is your identity. Partners address you by an EDI ID. If that ID is yours and it comes with you, then for many partners nothing visibly changes. If it was issued by your provider and stays behind, every partner has to change where they send your documents, and some will want to test before they do.
So ask before you commit to anything new: does my ID come with me? Some providers can move it and some cannot.
Certificates are the other small chore. Partners on a direct AS2 link each have a certificate that expires and has to be renewed with that partner. Your provider has been doing this in the background. Once it is yours it is light work, mostly keeping an eye on dates, but it is work.
The maps are the work
Maps are where the effort goes, because no two partners use the standard the same way. Two retailers on the same version of X12 still publish their own implementation guides on top of it, and those guides decide which optional fields become mandatory, which codes are allowed, and how an item has to be identified. We went into that in connecting isn't the work.
Then there is your side. The same purchase order has to land in your system with the right item, the right unit and the right ship-to, every single time.
A full-service provider built all of that partner by partner, and has been adjusting it ever since. That accumulated adjustment is the real thing you are replacing, and it is exactly why doing the whole move in one weekend is a gamble.
Run them side by side
So don't switch. Run both.
Get copies of the real documents your partners send you, and the ones you send them. How easy that is depends on your provider and your plan, so ask early. Then build the new maps, run the same documents through the new setup, and compare what comes out against what your current provider produced.
For documents coming in, compare what lands in your system. For documents going out, compare the files each setup would send.
When a partner's output matches consistently, move that one partner over. Start with the simplest ones, with few document types and clean data. Leave your biggest accounts until last, by which point the process has already been through plenty of easier cutovers.
Your old provider is the answer key the whole way through. Nothing moves until the new setup has already matched it on your own documents.
What "matches consistently" should mean
A quiet week of plain orders proves very little. The documents that break a migration are the awkward ones: order changes and cancellations, partial shipments, backorders, multiple ship-to locations, credits. Make sure the comparison window includes them, or put them through on purpose.
And decide what counts as a match before you look at the results. Something like: every document for this partner over the last few weeks matches, and anything that didn't has a known reason. Otherwise it is very tempting to call it close enough.
What running side by side doesn't fix
Partners still test on their own calendar. If something changes on their side of the connection and they want to re-test you, the timing is theirs, not yours.
Rare documents may never show up. If a partner sends something twice a year, your comparison window won't see it unless you go looking. List those documents and test them deliberately.
You will pay for both for a while. Running side by side means overlapping with your current contract. Check your notice period early, and start well ahead of the renewal date rather than the month before it.
When it's worth doing
It is worth the effort when a renewal is coming up and you would rather decide on your own terms, when you are changing ERP anyway and the maps need rebuilding regardless, or when you would simply like your maps to be yours.
That's the migration we do: new maps built next to your current provider, compared on your own documents, partners moved over one at a time. If that sounds like where you are, get in touch.
PDFs, scans or emails in. Spec-compliant EDI out, returned within 48 hours, no commitment.