Voice API Programming Guide — June 2005 83
Call Progress Analysis
Figure 11. No Ringback Due to Continuous No Signal
If the length of any period of nonsilence exceeds the value of ca_cnosil (continuous nonsilence), a
no ringback is returned, shown in Figure 12.
ca_cnosil
Continuous Nonsilence: the maximum length of nonsilence allowed. If exceeded, a no
ringback is returned. Default: 650 (in 10 msec units), or 6.5 seconds.
Figure 12. No Ringback Due to Continuous Nonsilence
7.16.5.3 Cadence Detection Parameters Affecting a No Answer or Busy
By using the ca_nbrdna parameter, you can set the maximum number of ring cadence repetitions
that will be detected before returning a no answer.
By using the ca_nbrdna and ca_nsbusy parameters, you can set the maximum number of busy
cadence repetitions.
ca_nbrdna
Number of Rings Before Detecting No Answer: the number of single or double rings to wait
before returning a no answer. Default: 4.
CA_STDELY
250
CA_CNOSIG
4000
No Ringback
Returned
The timings are given in units of 10ms.
nonsilence
silence
Dialing
Complete
The timings are given in units of 10ms.
nonsilence
silence
CA_CNOSIL
650
No Ringback
Returned