It all depend on what one want to do, and what ones business model is.
Looking at the Opencall website, your are only selling it as a hosted service and not as a product. Both GPL and BSD will allow someone to create a competing hosting service and add any proprietary addition to it without having to share it back. AGPL would make sure that any such addition is shared back, so your business will always has access to improved versions.
Contributor Agreement is irrelevant since you won't need one if you just do hosting.
Contributor Agreement is absolutely relevant. If there is any chance that the project will accept patches from random people then release those patches as part of the core code base under a license .... you need a contributors agreement.
Given that OpenCall is Open Source, this is very possible.
Good point re diff between on GPL/BSD and AGPL. Tho if I may add, AGPL will only state that in writing. A bad company may break that, and then it's up to how willing you are to get legal on them to enforce the AGPL. Some people may be unwilling to do this, so this may play into the choice of license you go for.
Looking at the Opencall website, your are only selling it as a hosted service and not as a product. Both GPL and BSD will allow someone to create a competing hosting service and add any proprietary addition to it without having to share it back. AGPL would make sure that any such addition is shared back, so your business will always has access to improved versions.
Contributor Agreement is irrelevant since you won't need one if you just do hosting.