Hi Asaf,
ITU E.733
http://www.catr.cn/radar/itut/201007/P020100707513092084587.pdf
the topic of this document is to describe what is the max load of a SS7 link. I didn’t go much in the details, but it looks to me that “pmax” is chosen between 0.2 and 0.4 (chapter 7), and that all explanations are written in the previous chapters.
But it is not 0.2 erlang, it is just a factor = 0.2.
“7.1 Signalling link dimensioning objectives
Signalling links should be dimensioned so that the link utilization, ρ, does not exceed a maximum
utilization, ρmax, when there are no failures in the network. To handle failures, the link should be able
to support a utilization of 2ρmax. The signalling load that determines the link utilization, ρ, is
determined as described in clause 6.”
Regards
pix