AT&T Circuit Migration

Since 2003, the California ISO has contracted with AT&T to provide secure data communications between the ISO and its Market Participants. AT&T provides for secure data communications via a nationwide virtual private data network that we call the ISO Energy Communications Network (ECN).

Since 2003, each Market Participant who connects to the ISO ECN has done so via digital communications technology called “time division multiplexing” (TDM). The most common TDM connection is referred to as a “T1”. Historically, every Market Participant who connects to the ECN with a T1 line is financially responsible for the cost of those lines, via a contract with AT&T. AT&T provides these connections at a discounted rate as part of an affiliation with ISO’s master services agreement with AT&T.

Over the past 20 years, communications technology has changed significantly. As communications equipment manufacturers no longer provide these legacy TDM services hardware, AT&T and other providers are no longer able to provide the same level of service to customers and are therefore migrating customers to current communications technologies. AT&T and other service providers have invested significantly in replacing their communications network infrastructure over many years, and customers (including ISO Market Participants) need to migrate to these new technologies as soon as possible.

Due to the challenges AT&T has in supporting these legacy TDM services, they have been rapidly increasing the monthly rates for these TDM services. Since ISO has a long term contract with AT&T, our customers have not yet experienced these rate increases. However, ISO’s contract agreements with AT&T are set to expire at year end and must be renewed. AT&T cannot support an extension of the current monthly costs for TDM services into the new contract; AT&T has also expressed concerns that it is paying significantly more to the local exchange carriers (LECs) and cannot continue to absorb these cost increases long term.

The ISO is now working with AT&T to migrate all of the current TDM services, but this effort requires resources and attention from each generation resource owner and operator with TDM connections to the ISO’s ECN network. The ISO and AT&T will need up to date technical contacts to work directly with; these technical contacts need to be familiar with the telecommunications circuits and associated communications equipment (routers etc.) at each generation substation and have physical access to the generation facilities where these communication services are installed. The ISO is requesting each generation owner / operator prioritize this effort and make every effort to provide the appropriate technical resources and make those resources available to facilitate these technology migrations with the appropriate urgency. In the meantime and until the migration occurs, the exiting TDM T1 services will continue to function but it is expected that AT&T will assess higher monthly rates, beginning in January. Those costs will vary based on a number of variables; the new monthly cost of each T1 will be highly discounted from retail rates starting in Q1, and those discounts will decrease (therefore rates increasing) each Quarter going forward. This is a financial incentive for all connections to migrate to new access technology as quickly as possible.

ACTION REQUIRED: You must reply via email to Katie Stevens at kstevens@caiso.com and acknowledge receipt of this notice by Jan. 17, 2025. Your acknowledgment will help the ISO and AT&T confirm contact information for your telecommunication circuits connected to the ISO’s ECN network.