While most OSS components such as billing, order entry and CRM are services-intensive, provisioning systems are no exception. Most of these products provide toolkits to build custom processes for provisioning and service activation.
Unfortunately few vendors will share common processes, even for similar equipment. This means that you need to pay a lot of money for services to deploy, configure, customize and maintain the system in your unique environment.
While they can pay dividends over time, try to build as much internal capabilities and knowledge around the product as possible to keep services costs to a minimum.
The vendors' professional services group, as well as many of the large system integrators will bring individuals to the table that understand a narrow slice of the technology and often build massive teams to deploy the solutions. Having cross-training staff that understand the architecture, development and usability will be much more beneficial to the organization and help reduce the team size, cost and chances for success.