| ??? 09/11/08 18:25 Read: times |
#158198 - DTMF over GSM Responding to: ???'s previous message |
Per Westermark said:
Yes, "analog" transfer of DTMF over GSM is very tricky. It can work like a charm with one GSM operator and fail badly with another. The GSM phone can send digital commands to get the phone system to generate the DTMF tones within the network. But the problem is to receive and detect DTMF tones sent in the other direction in the voice channel. Correct. When you press the buttons on your mobile phone, the phone does not generate DTMF locally and send it in-band as audio; instead, it goes in the (digital) signalling channels and the audio DTMF is generated by the network. Also, the GSM codecs are not particularly optimised for DTMF. However, Wavecom are claiming that their latest offerings do have the capability to detect & decode incoming in-band DTMF. I haven't tried it - perhaps you should seek out your local distributor for further info and a demo...? Where is the 8051 in all this? |
| Topic | Author | Date |
| IVR using GSM | 01/01/70 00:00 | |
| DTMF problematic | 01/01/70 00:00 | |
| DTMF over GSM | 01/01/70 00:00 | |
| 8051 | 01/01/70 00:00 | |
| wavecom | 01/01/70 00:00 | |
| voice | 01/01/70 00:00 | |
| uLaw or similar | 01/01/70 00:00 | |
| Digital sound? | 01/01/70 00:00 | |
| MP3 if very mouch speech info | 01/01/70 00:00 | |
| MP3 is a poor speech codec | 01/01/70 00:00 | |
"Optimum" not always optimum | 01/01/70 00:00 |