The 5ESS® is a multi-service, software-based digital switch made by Lucent Technologies' Switching Access Systems division. It is a reliable telephone switching system developed by Bell Labs and is in use on PSTNs worldwide. The 5ESS® handles any combination of wireline, wireless, voice, data and video services from the same switch. The 5ESS® is modular and capable of up to 250,000 subscriber lines and over 100,000 trunk lines.