Poor quality music on hold on external calls - SV9500

[phadobas]

I have an SV9500. It has 3 PIMs for some analog line cards and PRI cards, and otherwise the terminals are 90% IP terminals. The music on hold is played by an MP3 player and its output is punched down on the EXT/ALM cable.

On internal calls (IP-to-IP or IP-to-TDM) the music plays just fine. However on external calls, be it incoming or outgoing, which are handled by different routes and different telco-s, the music gets distorted. There are sections of the music that are playing OK, and other sections are just a distorted mess. It's alwaus the same sections that are distored.

Those incoming / outgoing routes have been handled by the same teclo and the same PA-PRT cards. I just did one more round of tests and actually noted that the problem occurs only if the external caller/called person is using a cell phone. If the external person is on a landline, the music sounds clean.

So I have:
MUSIC - TDSW - IPPAD card - IP phone - IP phone: sounds great
MUSIC - TDSW - PA PRT Card - Telco - landline: music sounds great
MUSIC - TDSW - PA PRT Card - Telco - mobile used: music is a distorted mess

Anybodo has any ideas?

 

[OldNECguy]

Sounds like you may be a victim of VAD - Voice Activity Detection. If set on a VOIP connection, a router won't transmit RTP unless audio is detected. Could you turn up the source volume and see it it makes a difference, at least for a test?

 

[phadobas]

I did increase the volume for testing, but unfortunately it didn't solve the problem. The music got louder and the distortion got louder.

 

[OldNECguy]

With it apparently affecting the same sections of audio, only on cellular calls, my next thought would be a frequency problem, that is an inability for a cellular network to replicate those frequencies. What is particular about those audio sections that is not true of the good audio sections? Have you tried other music/audio? With it affecting only cellular calls, there aren't many things you can change to affect it.

 

[wirerun]

I would try converting mp3 files on the player to 8-Bit, 8Khz, WAV file. Assuming their player can handle .wav format