[Asterisk-Users] Ztdummy - is it requirement?

[Philipp von Klitzing]

Hi!

> I am interested to learn if I need to have ztdummy installed if I do not
> have any zaptel hardware in my machine?

No, not necessarily. You'll only need it if you want to use MeetMe 
conferencing. Look here:

http://www.voip-info.org/tiki-index.php?page=Asterisk+timer

> I have found a lot of references with RTP problems which were related to
> RTP timing (or lack of it).
> 
> My problem is that voice coming from SIP hardware is OK, but voice going
> from asterisk to SIP hardware is choppy, full of noise or completely
> cut-off. Am I going to solve my problem with ztdummy (which btw. I can
> not compile but I see that this is also common problem)?

Most likely you have a slience suppression issue here, and that is not 
related to ztdummy. If you use X-Lite as SIP client then you'll need to  
make sure you have "Transmit Silence" set to YES. For other devices like 
Grandstream phones etc you'll find different names being used for the 
same thing (for example "VAD"). You can test this by constantly creating 
sound on your side when hearing "choppy sound" - if that fixes the 
problem then you have a silence suppression issue.

As for the noise I can only guess: 

- make sure you use a good SIP client (and a GOOD soundcard if this is a 
softclient; it might help if you told the list WHICH client you are 
working with, by the way, that'll cut down the guesswork)
- don't ever run X-Windows on your Asterisk server
- check your network and tell us what kind of connection you have between 
phone and Asterisk server; maybe your upload link Ast --> phone is too 
thin & too packed?
- are there rules as to when you get a) choppy sound, b) no sound and c) 
noise? Do you see that problem also with 1. voicemail and 2. music-on-
hold?
- what channel (technology) are you calling with your SIP device?

> What changes I have to make in modules.conf file in order to start using
> ztdummy?

Usually none - but see URL above for details: You'll need to edit the 
zaptel Makefile.

Cheers, Philipp