when i use ip phone 7960 dial pstn, why there are so many noise and delay?

[admin_2]

when I call using IP Phone 7960 to PSTN, I get a lot of noise and delay? My gateway is 2600 fxo, and use MGCP.

Why is this happenning and how can I solve it?

[#2]

Try disabling vad, and use g711.

Also try different phone just to make sure it's not the bad phone.