The type of EDI services to choose depends on the specific needs of your business, taking into account size, existing infrastructure and of course, budget.
Most existing EDI services are delivered via VAN (Value Added Network) which is a secure, private network where documents are sent and received between traders. However, in recent years there has been a growth in more flexible, low-cost approaches which although not implemented as widely, may provide a more suitable alternative.
For example, Web EDI allows the transfer of documents to conducted directly through an internet browser, which means the service can be easily rolled out among trading partners. It can also be particularly useful when working with partners in countries where EDI and IT skills are not as advanced.
There are many variables to consider, and pros and cons to each option.
A great resource to help you decide is: edibasics.co.uk which has invaluable information on choosing services and a provider.