What I have found to work best for verification calls :
1) Use G711 codec in ATA / IP Phone (PCMA or PCMU in Voxalot)
2) Use RTP (RFC2833)
3) Uncheck In audio (Inband), and SIP Info (some devices allow the selection of all three modes at the same time
4) Use a good quality corded phone (if using an ATA) as opposed to a cordless phone, as the transmission to the base may be degrading the DTMF tone quality at the receiving end
5) Use a delibrately longer dwell on each dialled number to give the receiving system a better chance to recognize the number. This is not possible with some phones which have a preset duration of each tone.
Hth...
|