VoIP - PHP for GoIP sim gateway API Development

Needed: Experienced PHP programmer for VoIP needed, knowledgeable in telecom programming particularly GoIP sim bank gateways, GoIP API programming, Asterisk A2Billing and FreePBX, and Cisco. Description: Create an API to control the actions of a GoIP sim bank gateway by Call Progress Tones. GoIP sim gateway is located in a third world country to which the selected contractor must program the proper Call Progress Tones. The GoIP sim bank gateway provides the termination into the country. A PHP program is then needed to conditionally control the Call Progress Tones that are sent back to the Asterisk on the origination side. The following acceptable Call Progress Tones (CPT), specific to the terminating country, should be selectably programmed to send back to the origination side: Ringing Tone Busy Tone Congestion Tone Dial Tone Number Unobtainable Tone Waiting Tone Holding Tone The GoIP sim bank gateways should conditionally act to capture any other Call Progress Tone, which essentially would represent an unwanted condition on the line, and redirect (hunt) the call to another available SIM across the GoIP gateways. This routine should continue until the GoIP can handle the call with the above acceptable Call Progress Tones. The API program should set a flag for the SIM that had the unwanted Call Progress Tone condition. The flag shall have an operator settable variable representing elapsed time prior to which another call may be sent to that particular SIM. For example, a set variable of 3 (three) would represent an elapsed time requirement of three minutes prior to the SIM card port being available to attempt another call. When this flag condition occurs, an SMS message should be sent to 4 phone numbers (set by data entry into variables) indicating the Sim on which this condition occurred. These numbers may be programmed in a separate data entry routine. If it is preferred to program this feature within the same CPT API routine it should have a time out feature (i.e. 1 min) so that the CPT API routine may continue unattended. This SMS send of the flag condition function should also be able to be turned off. The operator shall also identify the selected flag condition (one CPT in particularly) that this routine shall act on by use of the methods for diagnosing CPT described in the website below. A "CDR" reporting feature of unwanted CPT conditions is also needed. Sample Call Progress Tones for the subject country can be provided. Such information can be combined to provide a complete CPT solution. For example view: ftp://[login to view URL] The programmer shall be knowledgeable of the syntax to program Call Progress Tones within Asterisk, GoIP, etc. The presence of the Cisco in the solution is optional and removal from the solution will be considered. Programmer shall be familiar with the use of Audacity (or other program) to diagnose Call Progress Tones, as described at the following page: [login to view URL] Responders should provide a description of their experience. The system is equipped with the following: A2Billing version FreePBX version Running on Linux CentOS ver. 6.5 GoIP sim gateways with Operating System ( 2 units with 32 ports each ) connected to a single 128 port GoIP sim bank. A separate work station has the Session Controller operatiing with a MySQL database. Does each GoIP gateway have its own IP address or are they behind a NAT router? Ans: Each GoIP gateway has its own IP address and there is presently no router in front of the gateways.