Detecting events occurring on remote telephone
A process and a system are disclosed for detecting activity, e.g., three way calling, call forwarding, or the like, during a phone call. The process includes, and the system is configured for, establishing the call path between a first party and a second party, adding a reference tone to the call path, observing a reflected tone from the call path, and determining a relationship between the reference tone and the reflected tone. Information relating to the relationship may be reported for further analysis.
1. A method of detecting activity during a phone call, the method comprising:
establishing a call path between a first party and a second party;
adding a first reference tone of a first repetitive waveform to a first electrical signal from the first party to the second party via the call path during the phone call;
receiving a second electrical signal from the second party to the first party via the call path during the phone call, the second electrical signal including a reflected tone of a second repetitive waveform, the second repetitive waveform representing the first reference tone reflected from the call path; and
detecting change in a phase difference between the first reference tone in the first electrical signal and the reflected tone in the second electrical signal during the phone call to detect a three-way call attempt or a call transfer attempt.
2. The method of claim 1 , wherein detecting the change in the phase difference comprises determining a zero crossing of the reflected tone.
3. The method of claim 1 , wherein the frequency of the first reference tone is fixed.
4. The method of claim 1 , further comprising adding a second reference tone in the first electrical signal, the second reference tone in combination with the first electrical signal generating a first envelope in the first electrical signal and a second envelope in the reflected tone.
5. A method of detecting activity during a phone call, the method comprising:
establishing a call path between a first party and a second party;
adding a first reference tone of a first repetitive waveform to a first electrical signal from the first party to the second party via the call path;
adding a second reference tone to the first electrical signal of a second repetitive waveform, the second reference tone in conjunction with the first reference to generating a first tone envelope in the first electrical signal;
receiving a second electrical signal from the second party to the first party via the call path, the second electrical signal including a second tone envelope including a third repetitive waveform, the second tone envelope representing the first tone envelope reflected from the call path; and
detecting change in a phase difference between the first tone envelope in the first electrical signal and the second tone envelope in the second electrical signal.
6. The method of claim 5 , wherein detecting the change in the phase difference comprises comparing inflection points of the first tone envelope and the second tone envelope.
7. The method of claim 5 , wherein detecting the change in the phase difference comprises comparing one of minimum reference points and maximum reference points in the first tone envelope and the second tone envelope.
8. The method of claim 5 , wherein detecting the change in the phase difference comprises analyzing zero crossings of the first tone envelope and the second tone envelope.
9. The method of claim 5 , wherein the frequency of the first reference tone is fixed.
10. A system for detecting activity during a phone call, the system comprising:
a reference tone generator configured to generate a first reference tone of a first repetitive waveform during the phone call;
a summing module configured to add the first reference tone to a first electrical signal from a first party to a second party via an established call path during the phone call;
an interface configured to receive a second electrical signal from the second party to the first party via the call path during the phone call, the second electrical signal including a reflected tone of a second repetitive waveform, the second repetitive waveform representing the first reference tone reflected from the call path; and
a detection module configured to determine a change in a phase difference between the first reference tone in the first electrical signal and the reflected tone in the second electrical signal during the phone call to detect a three-way call attempt or a call transfer attempt.
11. The system of claim 10 , wherein the reference tone generator is further configured to generate a second reference tone, the summing module is further configured to add the second reference tone to the first electrical signal to generate a first tone envelope.
12. The system of claim 10 , wherein the first reference tone is between 150 and 600 Hz.
13. The system of claim 10 , wherein the phase difference is detected by a zero crossing of the first reflected tone and a zero crossing of the reflected tone.
14. The system of claim 10 , wherein the phase difference is determined by comparing inflection points of the first reference tone and the reflected tone.
15. The system of claim 10 , wherein the phase difference is determined by comparing one of minimum reference points and maximum reference points in the first reference tone and the reflected tone.
16. The system of claim 10 , wherein the phase difference is determined by comparing one of zero crossings, minimum reference points, and maximum reference points of the first reference tone and one of zero crossings, minimum reference points, and maximum reference points of the reflected tone.