General Telecom learning links::
Telco
Primer (USC)
Telco
VoIP (Cisco) [ Cisco.com is one of the best technical resource for both
data and telecom connectivity]
wireless market value chain
A good overview
from Cisco of the diffferent players in the long-haul VoIP/telco network
Incredibly documented
call flows for all things telecom
Technical links (about protocols):
Freeswitch Signling
IEEE
[A technical good overview of wireless communications – handset perspective]
Local Number Portability (LNP)