Need Help Regards Sim Server Solution

HI ,
I am looking for Call termination solution with Sim server , i already used teles , 2n , eurotech GSM gateways , but sim server is new for me
Regards Gsm gateways eurotech is good , 2n is very good and teles have high PDD issue
Now i heared regards quescom they are giving complete Calltermation solution with sim server , any body guide me which brand is best for sim servers
Quescom or any other

I will be thankful

support1982@hotmail.com