ITU-T Recommendation E.261 Telephone network and ISDN. Operation, numbering, routing and mobile service. Devices for measuring and recording call durations

ITU-T Recommendation E.260 Telephone network and ISDN. Operation, numbering, routing and mobile service. Basic technical problems concerning the measurement and recording of call durations ITU-T Recommendation E.232 Telephone network and ISDN. Operation, numbering, routing and mobile service. Charging for calls to subscriber’s station connected either to the absent subscriber’s service or to a device substituting a subscriber in his absence CCITT Recommendation E.230 Telephone network and ISDN. Operation, numbering, routing and mobile service. Chargeable duration of calls ITU-T Recommendation E.300 Telephone network and ISDN. Operation, numbering, routing and mobile service. Special uses of circuits normally employed for automatic telephone traffic ITU-T E.300-series Recommendations – Supplement 1 Series E: Overall network operation, telephone service, service operation and human factors… List of possible supplementary telephone services which may be offered to subscribers ITU-T E.300-series Recommendations – Supplement 3 Series E: Overall network operation, telephone service, service operation and human factors. Operation of the international service. North American precise audible tone plan