You haven't mentioned port types, but since you referenced disconnection , I think you are talking about FXO ports.

To enable tone based supervisory disconnect on the FXO ports, you will need the following :

!

voice-port 0/0/0

supervisory-disconnect dualtone mid-call

cptone

timeouts disconnect 3

timeouts wait-release 3

!

There is a cptone entry for Saudi Arabia -

CME-Switch(config-voiceport)#cptone ?

locale 2 letter ISO-3166 country code

AR Argentina IS Iceland PE Peru

AU Australia IN India PH Philippines

AT Austria ID Indonesia PL Poland

BE Belgium IE Ireland PT Portugal

BR Brazil IL Israel RU Russian Federation

CA Canada IT Italy SA Saudi Arabia

CN China JP Japan SG Singapore

CO Colombia JO Jordan SK Slovakia

C1 Custom1 KE Kenya SI Slovenia

C2 Custom2 KR Korea Republic ZA South Africa

CY Cyprus LB Lebanon ES Spain

CZ Czech Republic LU Luxembourg SE Sweden

DK Denmark MY Malaysia CH Switzerland

EG Egypt MX Mexico TW Taiwan

FI Finland NP Nepal TH Thailand

FR France NL Netherlands TR Turkey

DE Germany NZ New Zealand GB United Kingdom

GH Ghana NG Nigeria US United States

GR Greece NO Norway VE Venezuela

HK Hong Kong PK Pakistan ZW Zimbabwe

HU Hungary PA Panama

CME-Switch(config-voiceport)#cptone SA

Try this and make a call from the PSTN to the IP phone, then drop the call on the PSTN side.

It should disconnect the call after the disconnect tone plays for a few seconds.

If your hear a cycling/repeating tone, but the voice port does not disconnect, capture a wireshark trace from the voice vlan from the gateway router that has around 10 seconds of the actual disconnect tone and post it and we can analyse it and create a custom disconnect tone.