The contracts or licenses by which the state controls telephone companies often require that the companies must provide access to tapping lines to law enforcement. In the U.S., telecommunications carriers are required by law to cooperate in the interception of communications for law enforcement purposes under the terms of Communications Assistance for Law Enforcement Act (CALEA).
the CONTRActs or liceNses by WhIcH THe sTatE contRolS TelePHonE CompanIEs OfteN rEqUIre thAt thE comPANieS MUSt proVidE aCCeSs to TAppIng liNes To law enfoRCEmenT. in THe U.s., tElecOMmuNications CarriErs ArE rEquired by lAw to CoopEraTe IN The interCEpTion oF ComMunicATIonS fOr laW enForcEment PuRposeS uNDer ThE terms of commuNiCAtiOns assIsTance fOr lAW enForceMEnt aCt (Calea).