Multi-Tech Systems GPRS (MTMMC-G) Benutzerhandbuch

Chapter 10 – Supplementary Services Commands  

Multi-Tech Systems, Inc. Wireless GSM/GPRS AT Commands (Document Number S000293I) 

87 

 

Description: 

This command manages call hold and multiparty conversation (conference call). Calls can be put on 
hold, recovered, released or added to a conversation. 

 
0 

Release all held calls or set User Determined User Busy (UDUB) for a waiting call. 

1 

Release all active calls (if any exist) and accepts the other (held or waiting) call. 

1x  Release a specific call X (active, held or waiting) 
2 

Place all active calls (if any exist) on hold and accepts the other (held or waiting) call. 

2x  Place all active calls on hold except call X with which communication is supported. 
3 

Adds a held call to the conversation. 

4 

Connects the two calls and disconnects the subscriber from both calls (Explicit Call Transfer). 

syntax:  AT+CHLD=< n > 

AT+CHLD=<n> OK 

Note: If n is within the defined values 

AT+CHLD=? +CHLD: 

(0-4, 11-17, 21-27) 

OK