Telecommunication networks and methods are disclosed for providing a group session service for a plurality of participants. Disclosed is the non-invasive use of a luminescent compound to detect and measure concentrations of oxygen dissolved in solids, particularly polymeric materials present in multi-layered packaging materials. The communication style is determined by comparing the words and phrases contained within the communication with conventional neuro-linguistic and brain dominance models and theories. Large delays are accomplished by changing the relationship between the WR and RD clocks in whole clock intervals. A relief valve is installed at one of the casings. The retransmitted data packets being retransmitted in form of a selected one of a plurality of different redundancy versions.