Four mobile toys that I crossed with office VoIP / SIP telephony: nokia e51 (Symbian), HP 514 & HTC Diamond (Windows Mobile), Samsung i7500 (Android)
The last four mobile toys that I crossed with office VoIP / SIP telephony: nokia e51 (Symbian), HP 514 and HTC Diamond (Windows Mobile), Samsung i7500 (Android). As shown by the operation, only Nokia E and N series are suitable. Alas. But at Nokia, the quality of VoIP / SIP performance is better than with GSM.
I was especially offended when I heard the grunt of “HP iPAQ 514 Voice Messenger” - I bought it exclusively because of the official declared work of VoIP / SIP in the main functionality of the phone ... but it distorts the sound very much, the voice cannot be recognized without long painful addiction. Yes, and no volume. The implementation is simply monstrous, but the manufacturer of HP in the firmware update was only able to slightly increase the volume. I also tested it on HTC Diamond - the same problems, as I understood it, are a global problem of implementing VoIP in Windows Mobile itself. For Mobile, there are two software dialers: Fring and PortaSIP, they have no problems with voice quality, but they are not as good as usability, you can use them for tests and call once a day, but not more. Even on Windows Mobile, the battery eats with normal office use - in 2-3 hours, the problem of Windows is also incurable.
Samsung with android in the database does not know how, it is necessary to put a SIP client on it. From fully integrated into the dialer, I found only one - Sipdroid. I set up, connected ... and heard all the same grunting, as in Windows. I read the forums of the developers of the droid, they say the problem in the application of float-point algorithms on integer processes. Prots in mobile phones cannot work with floating point numbers, and the voice processing algorithms for integer percents are not sharpened. The correct algorithms for working with float on fixed are time consuming and require greater performance. In general, on DSP processors, high-quality algorithms for implementing VoIP (codec, e-mail, jitter suppression algorithms) use about 10-25 MIPS per channel depending on codecs, for modern phones it is less than 10% of performance. Either the code is written lazily, or just jambs ... but there are problems and when they are solved incomprehensibly.
I was especially offended when I heard the grunt of “HP iPAQ 514 Voice Messenger” - I bought it exclusively because of the official declared work of VoIP / SIP in the main functionality of the phone ... but it distorts the sound very much, the voice cannot be recognized without long painful addiction. Yes, and no volume. The implementation is simply monstrous, but the manufacturer of HP in the firmware update was only able to slightly increase the volume. I also tested it on HTC Diamond - the same problems, as I understood it, are a global problem of implementing VoIP in Windows Mobile itself. For Mobile, there are two software dialers: Fring and PortaSIP, they have no problems with voice quality, but they are not as good as usability, you can use them for tests and call once a day, but not more. Even on Windows Mobile, the battery eats with normal office use - in 2-3 hours, the problem of Windows is also incurable.
Samsung with android in the database does not know how, it is necessary to put a SIP client on it. From fully integrated into the dialer, I found only one - Sipdroid. I set up, connected ... and heard all the same grunting, as in Windows. I read the forums of the developers of the droid, they say the problem in the application of float-point algorithms on integer processes. Prots in mobile phones cannot work with floating point numbers, and the voice processing algorithms for integer percents are not sharpened. The correct algorithms for working with float on fixed are time consuming and require greater performance. In general, on DSP processors, high-quality algorithms for implementing VoIP (codec, e-mail, jitter suppression algorithms) use about 10-25 MIPS per channel depending on codecs, for modern phones it is less than 10% of performance. Either the code is written lazily, or just jambs ... but there are problems and when they are solved incomprehensibly.
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Source: https://habr.com/ru/post/78376/
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