Build a Fully Functional SMS Sending System using SIP

We are looking for someone to build a fully functional SMS System.
The primary market would be here in South Africa, though we also looking to send further afield such as UK, USA and Australia, for clients based there.
Would need full reporting to be available, on the SMS sent, such as delivered, pending and undelivered and be able to export into csv.
Full viewing history of all campaigns/sms sent and ability to export results.
Ability for clients to create a login and accounts from website.
Enable price fixing for each account so credits applied automatically once payment received is input on the system, again full viewing history of payments.
Bulk import and export.
Blacklist to be kept by client for each campaign they have rather than per account.
Start/Send times to be specified by client, Monday to Sunday 00.00 – 24.00; enable to be changed as required.

System Requirements
In terms of the system, we want to make use of VoIP/SIP Trunks to send SMS, as this appears to be by far and away the cheapest method.
Each SIP trunk could send approc 12,000 SMS per hour and the costs of the trunk are approx. 20 USD.
The idea is to pool the SIP trunks rather than allocate to each account, this way they are maximised across all clients.
Longcodes required for each campaign rather than per account, again you are required to source these also. ideally, we need system we can take over and order SIP trunks to system and longcodes as required, rather than trouble you. With a pooling system, Clients to have a ‘sending rating’ also so that a priority can be applied to SMS in queue making use of the trunks available. Priority 1 – takes precedent Priority 2 – only sends when there is capacity to do so and Priority 3 – would be for our own use based on availability.

Let me know your thoughts on this.
Full database to be held centrally also of all sms sent.
Ideally when importing if they can add other fields such as Name etc., so that when replies are received and they come to export, this information is also available, rather than just the cellphone number, as well as the campaign ID that the SMS was sent from.

We also want to look at the possibility of bulk whatsapp and what that would entail.