If the call is not to an external number & if its to an internal number within the organisation, does it need stripping of digits?
We normaly don't use digit strip for extensions to extension call, for example user A extension 200 and user b extension 201, in this scenario no need of digit strip. you can dial each other by extensions number.
When to use digit strip.
Pstn call
Outgoing call
For example, assume that you use access code 9 for outgoing calls. when calling an 8 digit GSm number(99028165) you will dial 999028165 if you send this number to ISP, they will reject the call saying invalid number. so in this case you need to strip the access code 9. and send only the 8 digit GSm number which will be 99028165.
Incoming call.
For example assume that your DID is 24586201 and extensions configured on the phone is 201.
if ISP send full digit 2458620, your call processing sever will not be able to process it. because configured extension is 201 and call manger will not know what to do with 2458620. so you need to strip 24586.
For the same DID and configured extension, If you receive 3 digit from ISP, called number 201 you don't need to strip.
Trunk calls
If Office A and Office B use same range of extension, for example if both office use 2XXX range extensions, we normally add an extra digit before sending the call and strip when receiving.
The use of digit strip depend on the scenario. the above mentioned are just a few informations. these things change with scenarios.
Go through below link or google it, there are so many contents available.
https://www.ciscopress.com/articles/article.asp?p=1745737&seqNum=5
