Clients cant reply my text message

My clients are complaining that they can’t reply my text messages, I tried to change the text message configuration using my phone number as message originator, but I keep getting a message that my phone number is invalid. I sent a message to textanywhere for assistance, Kindly find below their response.
Regards 

–Date: 12/31/2013 1:32:46 AM
–Subject: TextAnywhere
Hi Eniola,
 
Many thanks for contacting us. The message originator would be controlled by the Clinic Office software and generally would give you two options – either a “no reply” option where you can send the message with 11 characters to identify the sender in which case the recipient would not be able to respond by text in which case you may want to include a number in the message body for them to call, or a reply option in which case a TextAnywhere reply path number is added. The problem with this may be that this would be a UK number and if your recipients are not UK based they would incur an international rate charge from their network to respond.
 
It may be possible to set the no reply option as a local number – we are not familiar with all the Clinic Office functionality as it is not our software – I would suggest that you contact them directly and I believe they should be able to advise you how best to set the local number.
 
Please do let us know if we can be of any further assistance.
 
Kind regards,
Mark Bruen