|Subject:||Inband Digits - what are they?|
|Category:||Unified MailCall, DTMF, Inband Digits|
|Summary||Inband digits are signals sent on the telephone line before the PBX connects the calling party to the called party.|
|Technical description||The term "Inband" is rather misleading when used to distinguish different types of DTMF digits that can come in. Inband really means that they are in the normal audio frequency of the telephone. The term inband doesn't say anything about WHEN digits come in, just HOW they come in. Conventionally, Inband digits have come to mean digits that are sent on the telephone line before the PBX connects the calling party to the called party. These digits are not sent until the called party answers the phone.|
|Relevance to Unified MailCall||Unified MailCall goes farther and says that anything that comes in as inband (Again, strictly based on the time that they come in) will be treated as the PBX trying to leave a message for the specified user. Anything else that comes in will be treated and the caller trying to navigate the menus.|
Now from the Unified MailCall point of view Unified MailCall is the called party. When it answers the phone and starts reading digits, it has no idea if the digits it is reading are the ones the PBX considers "Inband" or not. That is why there is an inband wait time. It is an arbitrary time that Unified MailCall can use as a cutoff and say anything before is inband and anything after is the caller pressing keys.
Let's say for example that the PBX is sending the string "1234". If the inband wait time is such that this string comes in as "Inband" (Not to harp on this, but it is strictly based on perspecitve) Unified MailCall will try to leave a message for "1234". If the string comes in after the inband wait time, Unified MailCall will assume the caller pressed "1234" from the main menu. This is interpreted as "try to connect to extension 1234".
To sum up, the PBX is sending the string "1234". If it sends this string AFTER the inband wait time has elapsed they will NOT be inband digits. If the digits come in BEFORE the inband wait time has elapsed, they WILL be considered "Inband". This inband wait time is no way connected to the PBX except for the fact that it must be long enough for the PBX to send all digits. Clear as mud!