47 CFR 61.25: References to other instruments.

In addition to the cross-references permitted pursuant to § 61.74, a non-dominant carrier may cross-reference in its tariff publication only the rate provisions of another carrier's FCC tariff publication, provided that the following conditions are met:

(a) The tariff being cross-referenced must be on file with the Commission and in effect;

(b) The issuing carrier must specifically identify in its tariff the cross-referenced tariff by Carrier Name and FCC Tariff Number;

(c) The issuing carrier must specifically identify in its tariff the rates being cross-referenced so as to leave no doubt as to the exact rates that will apply, including but not limited to any applicable credits, discounts, promotions; and

(d) The issuing carrier must keep its cross-references current.