| 摘要 |
The present invention discloses a method for serving character message transmission during a telephone call over PSTN connected to the central office to which information terminals having displays are connected for telephone calls and for data communication, the method including the steps of: based on SMS message writing and transmission request for use of character message transmission service of the first information telephone subscriber during a telephone call between a first and a second information telephone subscribers among the information telephones, if the customer premise equipment (CPE) alerting signal (CAS) is transmitted from the first information telephone in order to secure data transmitting/receiving reliability, muting, at the first information telephone, a handset of the first information telephone, transferring the CAS to the second information telephone through the central office in order to data transmitting/receiving reliability, and receiving a first acknowledge (ACK) message in response; after receiving the first ACK message, transferring, at the first information telephone, a message to the second information telephone through the central office for notifying the second information telephone to get prepared for receiving the written SMS message, and receiving a second ACK message in response; after receiving the second ACK message, transferring, at the first information telephone, the written SMS message to the second information telephone through the central office, and receiving a third ACK message in response; and after receiving the third ACK message, releasing, at the first information telephone, the handset of the first information telephone, and maintaining a busy state between the first and the second information telephone subscribers. |
