5 years as senior TIER III tech support for a "carriers carrier" (we carried customer data across telco zones to cut the tariffs ) My first 10 years started out installing Lucent OC48's in telco co locations and large customer comm rooms Then we went to Lambda Unites 4x OC192's and finally Infinera DTN OC 768. I also installed ALU MDR 4000's, 6000's & 8000's, UPS systems, 2-wire, 4-wire, 4-wire w/E&M signaling, data circuits across multiple platforms, example; At a power sub station from phone to telco or RFL channel bank to a T1/OC1 MUX mapped to local Lucent DMX then to Lambda Unite or Infinera DTN then to digital phone switch. I spent months out of town building new comm systems or upgrading existing links.