Establishing multiple bluetooth SPPs at the same time

Question

From my understanding I can only connect to a single service of a certain UUID. I looked in the properties and found that each device had it's own comport and guessed I had to be wrong. I tested multiple connections with 32feet.net and it turns out I can connect and communicate to both at the same time (and receive data).

I read Android: How do bluetooth UUIDs work? . Which mentions I need to the UUID to connect to a serial port service which I do and this is great (https://groups.google.com/forum/#!topic/android-developers/adeBD275u30) this link has the discussion.

I had been under the impression from reading various posts about not being able to connect to multiple headphones / keyboards / mice that bluetooth didn't allow you to connect to multiple services of the same UUID on Android / Iphone. Are these restrictions made by the OS / application?

After reading wikipedia / http://people.csail.mit.edu/rudolph/Teaching/Articles/PartOfBTBook.pdf that seems to be the case.

Did I just assume this a long time ago and forget that it was assumed from something non concrete?

Answer 1

Device A can connect only one at a time to service S on Device B. Device A can connect to service S on Device B, C, D and E, etc at the same time.

In details a RFCOMM service listens on port number and publishes that port number in a SDP record listed by UUID. Unlike TCP/IP which uses source and destination port numbers in its packets RFCOMM only uses one port number in its packets and therefore only one connection can be active to that port number between a pair of devices.